diff --git a/python/paddle/compat.py b/python/paddle/compat.py
index 886a787623ed18cd4b7a56f7ac6661f5f7bc6800..82e6491b8095505f0aed99f117bdd9eba6e8f3d7 100644
--- a/python/paddle/compat.py
+++ b/python/paddle/compat.py
@@ -17,12 +17,8 @@ import math
 
 __all__ = []
 
-if six.PY2:
-    int_type = int
-    long_type = long  # noqa: F821
-else:
-    int_type = int
-    long_type = int
+int_type = int
+long_type = int
 
 
 #  str and bytes related functions
@@ -262,7 +258,4 @@ def get_exception_message(exc):
     """
     assert exc is not None
 
-    if six.PY2:
-        return exc.message
-    else:
-        return str(exc)
+    return str(exc)
diff --git a/python/paddle/dataset/cifar.py b/python/paddle/dataset/cifar.py
index 9a9f9018e421618b4699121b59f6620a240d53a5..b33f1314f623d65f7169c09c800dba8fa8cae072 100644
--- a/python/paddle/dataset/cifar.py
+++ b/python/paddle/dataset/cifar.py
@@ -62,11 +62,7 @@ def reader_creator(filename, sub_name, cycle=False):
                          if sub_name in each_item.name)
 
                 for name in names:
-                    if six.PY2:
-                        batch = pickle.load(f.extractfile(name))
-                    else:
-                        batch = pickle.load(
-                            f.extractfile(name), encoding='bytes')
+                    batch = pickle.load(f.extractfile(name), encoding='bytes')
                     for item in read_batch(batch):
                         yield item
 
diff --git a/python/paddle/dataset/common.py b/python/paddle/dataset/common.py
index b712729f6420d019f1c1b5599f8e85cfef1a3765..71f469b92e4a783b5676937edb41f4881eb76b45 100644
--- a/python/paddle/dataset/common.py
+++ b/python/paddle/dataset/common.py
@@ -101,8 +101,6 @@ def download(url, module_name, md5sum, save_name=None):
                     bar = paddle.hapi.progressbar.ProgressBar(
                         total_iter, name='item')
                     for data in r.iter_content(chunk_size=chunk_size):
-                        if six.PY2:
-                            data = six.b(data)
                         f.write(data)
                         log_index += 1
                         bar.update(log_index, {})
diff --git a/python/paddle/dataset/flowers.py b/python/paddle/dataset/flowers.py
index 2f38c563136d3bb2cd3d84b3c6971ca03fe3d302..45a4c36f42ecd5929354b3a23933e08f5f80168b 100644
--- a/python/paddle/dataset/flowers.py
+++ b/python/paddle/dataset/flowers.py
@@ -132,10 +132,7 @@ def reader_creator(data_file,
                     file = file.strip()
                     batch = None
                     with open(file, 'rb') as f:
-                        if six.PY2:
-                            batch = pickle.load(f)
-                        else:
-                            batch = pickle.load(f, encoding='bytes')
+                        batch = pickle.load(f, encoding='bytes')
 
                         if six.PY3:
                             batch = cpt.to_text(batch)
diff --git a/python/paddle/distributed/fleet/utils/http_server.py b/python/paddle/distributed/fleet/utils/http_server.py
index a9d0687461b995e9d24390d1004bd38a52922c80..7d30fc5e0dff0db68be26171bd8563e162d8a23b 100644
--- a/python/paddle/distributed/fleet/utils/http_server.py
+++ b/python/paddle/distributed/fleet/utils/http_server.py
@@ -17,12 +17,8 @@ import logging
 
 import six
 # NOTE: HTTPServer has a different name in python2 and python3
-if six.PY2:
-    from BaseHTTPServer import HTTPServer
-    import SimpleHTTPServer
-else:
-    from http.server import HTTPServer
-    import http.server as SimpleHTTPServer
+from http.server import HTTPServer
+import http.server as SimpleHTTPServer
 
 import time
 import threading
diff --git a/python/paddle/fluid/contrib/slim/tests/quant2_int8_image_classification_comparison.py b/python/paddle/fluid/contrib/slim/tests/quant2_int8_image_classification_comparison.py
index 3fba0e892184953b300a54dd8590e07e81bc5f2d..188f14f0a6973300a7989d1a38d627a6a8f266e2 100644
--- a/python/paddle/fluid/contrib/slim/tests/quant2_int8_image_classification_comparison.py
+++ b/python/paddle/fluid/contrib/slim/tests/quant2_int8_image_classification_comparison.py
@@ -226,10 +226,7 @@ class Quant2Int8ImageClassificationComparisonTest(unittest.TestCase):
                 if iters == skip_batch_num:
                     total_samples = 0
                     infer_start_time = time.time()
-                if six.PY2:
-                    images = map(lambda x: x[0].reshape(dshape), data)
-                if six.PY3:
-                    images = list(map(lambda x: x[0].reshape(dshape), data))
+                images = list(map(lambda x: x[0].reshape(dshape), data))
                 images = np.array(images).astype('float32')
                 labels = np.array([x[1] for x in data]).astype('int64')
 
diff --git a/python/paddle/fluid/contrib/slim/tests/quant_int8_image_classification_comparison.py b/python/paddle/fluid/contrib/slim/tests/quant_int8_image_classification_comparison.py
index b81ef7b30ed4783133e46f7b895569db68438912..fac41ce8a22df73814cef4981f3723f18c990e91 100644
--- a/python/paddle/fluid/contrib/slim/tests/quant_int8_image_classification_comparison.py
+++ b/python/paddle/fluid/contrib/slim/tests/quant_int8_image_classification_comparison.py
@@ -196,10 +196,7 @@ class QuantInt8ImageClassificationComparisonTest(unittest.TestCase):
                 if iters == skip_batch_num:
                     total_samples = 0
                     infer_start_time = time.time()
-                if six.PY2:
-                    images = map(lambda x: x[0].reshape(dshape), data)
-                if six.PY3:
-                    images = list(map(lambda x: x[0].reshape(dshape), data))
+                images = list(map(lambda x: x[0].reshape(dshape), data))
                 images = np.array(images).astype('float32')
                 labels = np.array([x[1] for x in data]).astype('int64')
 
diff --git a/python/paddle/fluid/dataloader/dataloader_iter.py b/python/paddle/fluid/dataloader/dataloader_iter.py
index 1f928bfc8a6890ac2ba1bcc597538d41c5bfc0b2..17a57d510fa590d82d0a851a6b56c5b66e02fa94 100644
--- a/python/paddle/fluid/dataloader/dataloader_iter.py
+++ b/python/paddle/fluid/dataloader/dataloader_iter.py
@@ -27,10 +27,7 @@ from collections import namedtuple
 from paddle.fluid.framework import _set_expected_place, _current_expected_place
 
 # NOTE: queue has a different name in python2 and python3
-if six.PY2:
-    import Queue as queue
-else:
-    import queue
+import queue
 
 import paddle
 from .. import core, layers
diff --git a/python/paddle/fluid/dataloader/worker.py b/python/paddle/fluid/dataloader/worker.py
index 409f55efebc8a67647f82d06368d788b8fa3b7af..037cf2c4b12d2ac10c41f513c17246ea3f050549 100644
--- a/python/paddle/fluid/dataloader/worker.py
+++ b/python/paddle/fluid/dataloader/worker.py
@@ -26,10 +26,7 @@ from ..framework import in_dygraph_mode
 from .flat import _flatten_batch
 
 # NOTE: queue has a different name in python2 and python3
-if six.PY2:
-    import Queue as queue
-else:
-    import queue
+import queue
 
 __all__ = ['get_worker_info']
 
diff --git a/python/paddle/fluid/dygraph/checkpoint.py b/python/paddle/fluid/dygraph/checkpoint.py
index a18a6ed5c39854208cf876576a5acd970f11cc85..a98dc5a79aec3df77729908c8aa7482606dd9766 100644
--- a/python/paddle/fluid/dygraph/checkpoint.py
+++ b/python/paddle/fluid/dygraph/checkpoint.py
@@ -19,7 +19,6 @@ import collections
 import functools
 from ..framework import Variable, default_main_program, in_dygraph_mode, dygraph_only, Parameter, ParamBase, _varbase_creator, _dygraph_tracer
 import pickle
-import six
 from . import learning_rate_scheduler
 import warnings
 from .. import core
@@ -194,16 +193,14 @@ def load_dygraph(model_path, **configs):
         para_dict = {}
         if os.path.exists(params_file_path):
             with open(params_file_path, 'rb') as f:
-                para_dict = pickle.load(f) if six.PY2 else pickle.load(
-                    f, encoding='latin1')
+                para_dict = pickle.load(f, encoding='latin1')
 
         if not config.keep_name_table and "StructuredToParameterName@@" in para_dict:
             del para_dict["StructuredToParameterName@@"]
 
         if os.path.exists(opti_file_path):
             with open(opti_file_path, 'rb') as f:
-                opti_dict = pickle.load(f) if six.PY2 else pickle.load(
-                    f, encoding='latin1')
+                opti_dict = pickle.load(f, encoding='latin1')
     else:
         # check model path
         if not os.path.isdir(model_prefix):
diff --git a/python/paddle/fluid/dygraph/dygraph_to_static/utils.py b/python/paddle/fluid/dygraph/dygraph_to_static/utils.py
index f27501d1c35a347bac807aee8c21de43ce7e79e7..9a59111b32113f5ca7b42d4d6bc13b5cde480c70 100644
--- a/python/paddle/fluid/dygraph/dygraph_to_static/utils.py
+++ b/python/paddle/fluid/dygraph/dygraph_to_static/utils.py
@@ -60,10 +60,7 @@ class BaseNodeVisitor(gast.NodeVisitor):
 
 
 # imp is deprecated in python3
-if six.PY2:
-    import imp
-else:
-    from importlib.machinery import SourceFileLoader
+from importlib.machinery import SourceFileLoader
 
 dygraph_class_to_static_api = {
     "CosineDecay": "cosine_decay",
@@ -491,12 +488,8 @@ def ast_to_func(ast_root, dyfunc, delete_on_exit=True):
     import_fluid = "import paddle\nimport paddle.fluid as fluid\n"
     source = import_fluid + source
 
-    if six.PY2:
-        source = source.encode('utf-8')
-        f = tempfile.NamedTemporaryFile(mode='w', suffix='.py', delete=False)
-    else:
-        f = tempfile.NamedTemporaryFile(
-            mode='w', suffix='.py', delete=False, encoding='utf-8')
+    f = tempfile.NamedTemporaryFile(
+        mode='w', suffix='.py', delete=False, encoding='utf-8')
     with f:
         module_name = os.path.basename(f.name[:-3])
         f.write(source)
@@ -505,10 +498,7 @@ def ast_to_func(ast_root, dyfunc, delete_on_exit=True):
         atexit.register(lambda: remove_if_exit(f.name))
         atexit.register(lambda: remove_if_exit(f.name[:-3] + ".pyc"))
 
-    if six.PY2:
-        module = imp.load_source(module_name, f.name)
-    else:
-        module = SourceFileLoader(module_name, f.name).load_module()
+    module = SourceFileLoader(module_name, f.name).load_module()
     func_name = dyfunc.__name__
     # The 'forward' or 'another_forward' of 'TranslatedLayer' cannot be obtained
     # through 'func_name'. So set the special function name '__i_m_p_l__'.
diff --git a/python/paddle/fluid/dygraph/dygraph_to_static/variable_trans_func.py b/python/paddle/fluid/dygraph/dygraph_to_static/variable_trans_func.py
index 673d30cffbe1e3cc8e6223cf4036b1f90702d607..2877e10c64db5d6586f38d919f146b7fa898453d 100644
--- a/python/paddle/fluid/dygraph/dygraph_to_static/variable_trans_func.py
+++ b/python/paddle/fluid/dygraph/dygraph_to_static/variable_trans_func.py
@@ -98,17 +98,9 @@ def create_fill_constant_node(name, value):
         func_code += "dtype='float64', value={})".format(value)
         return gast.parse(func_code).body[0]
 
-    if six.PY2:
-        if isinstance(value, int):
-            func_code += "dtype='int32', value={})".format(value)
-            return gast.parse(func_code).body[0]
-        if isinstance(value, long):
-            func_code += "dtype='int64', value={})".format(value)
-            return gast.parse(func_code).body[0]
-    else:
-        if isinstance(value, int):
-            func_code += "dtype='int64', value={})".format(value)
-            return gast.parse(func_code).body[0]
+    if isinstance(value, int):
+        func_code += "dtype='int64', value={})".format(value)
+        return gast.parse(func_code).body[0]
 
 
 def to_static_variable(x):
diff --git a/python/paddle/fluid/dygraph/math_op_patch.py b/python/paddle/fluid/dygraph/math_op_patch.py
index 83804e80c2309b5b9c1df9907ceb9a37b29ba6b0..f6986265e2fbb319529fd8552b2d84f543be2f0c 100644
--- a/python/paddle/fluid/dygraph/math_op_patch.py
+++ b/python/paddle/fluid/dygraph/math_op_patch.py
@@ -20,7 +20,6 @@ from ..layers.layer_function_generator import OpProtoHolder
 from . import no_grad
 
 import numpy as np
-import six
 import warnings
 
 _supported_int_dtype_ = [
@@ -121,10 +120,7 @@ def monkey_patch_math_varbase():
         assert numel == 1, "only one element variable can be converted to long."
         tensor = var.value().get_tensor()
         assert tensor._is_initialized(), "variable's tensor is not initialized"
-        if six.PY2:
-            return long(var.numpy().flatten()[0])
-        else:
-            return int(var.numpy().flatten()[0])
+        return int(var.numpy().flatten()[0])
 
     def _int_(var):
         numel = np.prod(var.shape)
@@ -141,10 +137,7 @@ def monkey_patch_math_varbase():
         assert numel == 1, "only one element variable can be converted to python index."
         tensor = var.value().get_tensor()
         assert tensor._is_initialized(), "variable's tensor is not initialized"
-        if six.PY2:
-            return long(var.numpy().flatten()[0])
-        else:
-            return int(var.numpy().flatten()[0])
+        return int(var.numpy().flatten()[0])
 
     @property
     def _ndim_(var):
diff --git a/python/paddle/fluid/io.py b/python/paddle/fluid/io.py
index 2d3578c6c104b0753d881164b5feb15659986a1d..52cc7cdb2db4ca21ae94aae135e25c986266ef5b 100644
--- a/python/paddle/fluid/io.py
+++ b/python/paddle/fluid/io.py
@@ -1940,8 +1940,7 @@ def _pickle_loads_mac(path, f):
     max_bytes = 2**30
     for _ in range(0, file_size, max_bytes):
         pickle_bytes += f.read(max_bytes)
-    load_result = pickle.loads(pickle_bytes) if six.PY2 else pickle.loads(
-        pickle_bytes, encoding='latin1')
+    load_result = pickle.loads(pickle_bytes, encoding='latin1')
     return load_result
 
 
@@ -2113,8 +2112,7 @@ def load(program, model_path, executor=None, var_list=None):
         if sys.platform == 'darwin' and sys.version_info.major == 3:
             load_dict = _pickle_loads_mac(parameter_file_name, f)
         else:
-            load_dict = pickle.load(f) if six.PY2 else pickle.load(
-                f, encoding='latin1')
+            load_dict = pickle.load(f, encoding='latin1')
         load_dict = _pack_loaded_dict(load_dict)
     for v in parameter_list:
         assert v.name in load_dict, \
@@ -2135,8 +2133,7 @@ def load(program, model_path, executor=None, var_list=None):
                 optimizer_var_list, global_scope(), executor._default_executor)
 
         with open(opt_file_name, 'rb') as f:
-            load_dict = pickle.load(f) if six.PY2 else pickle.load(
-                f, encoding='latin1')
+            load_dict = pickle.load(f, encoding='latin1')
         for v in optimizer_var_list:
             assert v.name in load_dict, \
                 "Can not find [{}] in model file [{}]".format(
@@ -2297,15 +2294,13 @@ def load_program_state(model_path, var_list=None):
         if sys.platform == 'darwin' and sys.version_info.major == 3:
             para_dict = _pickle_loads_mac(parameter_file_name, f)
         else:
-            para_dict = pickle.load(f) if six.PY2 else pickle.load(
-                f, encoding='latin1')
+            para_dict = pickle.load(f, encoding='latin1')
     para_dict = _pack_loaded_dict(para_dict)
 
     opt_file_name = model_prefix + ".pdopt"
     if os.path.exists(opt_file_name):
         with open(opt_file_name, 'rb') as f:
-            opti_dict = pickle.load(f) if six.PY2 else pickle.load(
-                f, encoding='latin1')
+            opti_dict = pickle.load(f, encoding='latin1')
 
         para_dict.update(opti_dict)
 
diff --git a/python/paddle/fluid/layers/tensor.py b/python/paddle/fluid/layers/tensor.py
index 65cc745dbab8830be3c47a5a36fb7955d0bc4ea2..9d69b2f6706db0eaf5b24b9bd68227cdefaaa149 100644
--- a/python/paddle/fluid/layers/tensor.py
+++ b/python/paddle/fluid/layers/tensor.py
@@ -16,9 +16,7 @@ from __future__ import print_function
 
 import math
 import numpy
-import six
 import warnings
-from six.moves import reduce
 
 from ..layer_helper import LayerHelper
 from ..param_attr import ParamAttr
@@ -134,14 +132,9 @@ def create_parameter(shape,
     """
     check_type(shape, 'shape', (list, tuple, numpy.ndarray), 'create_parameter')
     for item in shape:
-        if six.PY2:
-            check_type(item, 'item of shape',
-                       (int, long, numpy.uint8, numpy.int8, numpy.int16,
-                        numpy.int32, numpy.int64), 'create_parameter')
-        else:
-            check_type(item, 'item of shape',
-                       (int, numpy.uint8, numpy.int8, numpy.int16, numpy.int32,
-                        numpy.int64), 'create_parameter')
+        check_type(item, 'item of shape',
+                   (int, numpy.uint8, numpy.int8, numpy.int16, numpy.int32,
+                    numpy.int64), 'create_parameter')
 
     check_dtype(dtype, 'dtype', [
         'bool', 'float16', 'float32', 'float64', 'int8', 'int16', 'int32',
@@ -194,14 +187,9 @@ def create_global_var(shape,
     check_type(shape, 'shape', (list, tuple, numpy.ndarray),
                'create_global_var')
     for item in shape:
-        if six.PY2:
-            check_type(item, 'item of shape',
-                       (int, long, numpy.uint8, numpy.int8, numpy.int16,
-                        numpy.int32, numpy.int64), 'create_global_var')
-        else:
-            check_type(item, 'item of shape',
-                       (int, numpy.uint8, numpy.int8, numpy.int16, numpy.int32,
-                        numpy.int64), 'create_global_var')
+        check_type(item, 'item of shape',
+                   (int, numpy.uint8, numpy.int8, numpy.int16, numpy.int32,
+                    numpy.int64), 'create_global_var')
 
     check_dtype(dtype, 'dtype', [
         'bool', 'float16', 'float32', 'float64', 'int8', 'int16', 'int32',
diff --git a/python/paddle/fluid/multiprocess_utils.py b/python/paddle/fluid/multiprocess_utils.py
index 82fb0f60b064fd1c8f02d4c73e7b8df97c9d6b56..d622172dced92184fa638da4a1c9b493c2162d2a 100644
--- a/python/paddle/fluid/multiprocess_utils.py
+++ b/python/paddle/fluid/multiprocess_utils.py
@@ -12,7 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import six
 import sys
 import signal
 import atexit
@@ -20,10 +19,7 @@ import atexit
 from . import core
 
 # NOTE: queue has a different name in python2 and python3
-if six.PY2:
-    import Queue as queue
-else:
-    import queue
+import queue
 
 # multi-process worker check indices queue interval, avoid
 # hanging in subprocess data loading
diff --git a/python/paddle/fluid/reader.py b/python/paddle/fluid/reader.py
index 616daf5a6504134c93720b31c66c1d19fb36b4ab..d5a23cfbdb9414fae7ad161e0de9dcc205b12c03 100644
--- a/python/paddle/fluid/reader.py
+++ b/python/paddle/fluid/reader.py
@@ -38,10 +38,7 @@ import multiprocessing
 import signal
 
 # NOTE: queue has a different name in python2 and python3
-if six.PY2:
-    import Queue as queue
-else:
-    import queue
+import queue
 
 # NOTE: [ avoid hanging & failed quickly ] These value is used in getting data from another process
 QUEUE_GET_TIMEOUT = 60
diff --git a/python/paddle/fluid/tests/unittests/dist_save_load.py b/python/paddle/fluid/tests/unittests/dist_save_load.py
index f3a6b19d819644aef24cc65dbc4bdea6bfd3b692..dd010e962e2a9b77671a4e9c8971886346c1bc0b 100644
--- a/python/paddle/fluid/tests/unittests/dist_save_load.py
+++ b/python/paddle/fluid/tests/unittests/dist_save_load.py
@@ -169,10 +169,7 @@ class TestDistSaveLoad2x2(TestDistSimnetBow2x2):
 
             var = np.array(fluid.global_scope().find_var('__fc_b__').get_tensor(
             ))
-            if six.PY2:
-                print(pickle.dumps(np.ravel(var).tolist()))
-            else:
-                sys.stdout.buffer.write(pickle.dumps(np.ravel(var).tolist()))
+            sys.stdout.buffer.write(pickle.dumps(np.ravel(var).tolist()))
 
         elif save_mode == "DIST":
             skip_steps = int(os.getenv("SKIP_STEPS"))
@@ -191,10 +188,7 @@ class TestDistSaveLoad2x2(TestDistSimnetBow2x2):
                         continue
                     loss, = exe.run(fetch_list=[avg_cost.name],
                                     feed=feeder.feed(data))
-            if six.PY2:
-                print(pickle.dumps(loss.tolist()))
-            else:
-                sys.stdout.buffer.write(pickle.dumps(loss.tolist()))
+            sys.stdout.buffer.write(pickle.dumps(loss.tolist()))
         else:
             raise Exception("save_mode must be LOCAL or DIST")
 
diff --git a/python/paddle/fluid/tests/unittests/dist_sharding_save.py b/python/paddle/fluid/tests/unittests/dist_sharding_save.py
index 676b15c0d93e761f7a331a4816d03005da0bf1df..99b2dcb97d1fbdd97ff3901ab194c16bd9666d5c 100755
--- a/python/paddle/fluid/tests/unittests/dist_sharding_save.py
+++ b/python/paddle/fluid/tests/unittests/dist_sharding_save.py
@@ -24,7 +24,6 @@ import paddle.distributed.fleet.base.role_maker as role_maker
 import paddle.distributed.fleet.meta_optimizers.sharding as sharding
 
 import os
-import six
 import sys
 import pickle
 
@@ -81,10 +80,7 @@ def runtime_main():
         exe, dirname, main_program=train_prog, filename=None)
 
     out_losses = []
-    if six.PY2:
-        print(pickle.dumps(out_losses))
-    else:
-        sys.stdout.buffer.write(pickle.dumps(out_losses))
+    sys.stdout.buffer.write(pickle.dumps(out_losses))
 
 
 if __name__ == "__main__":
diff --git a/python/paddle/fluid/tests/unittests/dist_text_classification.py b/python/paddle/fluid/tests/unittests/dist_text_classification.py
index 21180d7f49f56929df798e01b8d69aff371f2310..b96032b92eb982364a9610e033aa3680b052f052 100644
--- a/python/paddle/fluid/tests/unittests/dist_text_classification.py
+++ b/python/paddle/fluid/tests/unittests/dist_text_classification.py
@@ -44,14 +44,9 @@ DATA_MD5 = '29ebfc94f11aea9362bbb7f5e9d86b8a'
 # Load dictionary.
 def load_vocab(filename):
     vocab = {}
-    if six.PY2:
-        with open(filename, 'r') as f:
-            for idx, line in enumerate(f):
-                vocab[line.strip()] = idx
-    else:
-        with open(filename, 'r', encoding="utf-8") as f:
-            for idx, line in enumerate(f):
-                vocab[line.strip()] = idx
+    with open(filename, 'r', encoding="utf-8") as f:
+        for idx, line in enumerate(f):
+            vocab[line.strip()] = idx
     return vocab
 
 
diff --git a/python/paddle/fluid/tests/unittests/dygraph_to_static/test_logging_utils.py b/python/paddle/fluid/tests/unittests/dygraph_to_static/test_logging_utils.py
index b8a18179742df108d44dbf527adba819eefe91cd..2ed2a2733418058cb4ac2e64a9adbee282c76e4f 100644
--- a/python/paddle/fluid/tests/unittests/dygraph_to_static/test_logging_utils.py
+++ b/python/paddle/fluid/tests/unittests/dygraph_to_static/test_logging_utils.py
@@ -21,18 +21,10 @@ import sys
 import unittest
 
 import gast
-import six
 
 import paddle
 from paddle.fluid.dygraph.dygraph_to_static import logging_utils
-
-# TODO(liym27): library mock needs to be installed separately in PY2,
-#  but CI environment has not installed mock yet.
-#  After discuss with Tian Shuo, now use mock only in PY3, and use it in PY2 after CI installs it.
-if six.PY3:
-    from unittest import mock
-# else:
-#     import mock
+from unittest import mock
 
 
 class TestLoggingUtils(unittest.TestCase):
@@ -112,7 +104,7 @@ class TestLoggingUtils(unittest.TestCase):
                                            ast_code, "TestTransformer")
 
     def test_log_message(self):
-        stream = io.BytesIO() if six.PY2 else io.StringIO()
+        stream = io.StringIO()
         log = self.translator_logger.logger
         stdout_handler = logging.StreamHandler(stream)
         log.addHandler(stdout_handler)
@@ -122,39 +114,36 @@ class TestLoggingUtils(unittest.TestCase):
         log_msg_1 = "test_log_1"
         log_msg_2 = "test_log_2"
 
-        if six.PY3:
-            with mock.patch.object(sys, 'stdout', stream):
-                logging_utils.set_verbosity(1, False)
-                logging_utils.warn(warn_msg)
-                logging_utils.error(error_msg)
-                logging_utils.log(1, log_msg_1)
-                logging_utils.log(2, log_msg_2)
+        with mock.patch.object(sys, 'stdout', stream):
+            logging_utils.set_verbosity(1, False)
+            logging_utils.warn(warn_msg)
+            logging_utils.error(error_msg)
+            logging_utils.log(1, log_msg_1)
+            logging_utils.log(2, log_msg_2)
 
-            result_msg = '\n'.join(
-                [warn_msg, error_msg, "(Level 1) " + log_msg_1, ""])
-            self.assertEqual(result_msg, stream.getvalue())
+        result_msg = '\n'.join(
+            [warn_msg, error_msg, "(Level 1) " + log_msg_1, ""])
+        self.assertEqual(result_msg, stream.getvalue())
 
     def test_log_transformed_code(self):
         source_code = "x = 3"
         ast_code = gast.parse(source_code)
 
-        stream = io.BytesIO() if six.PY2 else io.StringIO()
+        stream = io.StringIO()
         log = self.translator_logger.logger
         stdout_handler = logging.StreamHandler(stream)
         log.addHandler(stdout_handler)
 
-        if six.PY3:
-            with mock.patch.object(sys, 'stdout', stream):
-                paddle.jit.set_code_level(1)
-                logging_utils.log_transformed_code(1, ast_code,
-                                                   "BasicApiTransformer")
+        with mock.patch.object(sys, 'stdout', stream):
+            paddle.jit.set_code_level(1)
+            logging_utils.log_transformed_code(1, ast_code,
+                                               "BasicApiTransformer")
 
-                paddle.jit.set_code_level()
-                logging_utils.log_transformed_code(
-                    logging_utils.LOG_AllTransformer, ast_code,
-                    "All Transformers")
+            paddle.jit.set_code_level()
+            logging_utils.log_transformed_code(logging_utils.LOG_AllTransformer,
+                                               ast_code, "All Transformers")
 
-            self.assertIn(source_code, stream.getvalue())
+        self.assertIn(source_code, stream.getvalue())
 
 
 if __name__ == '__main__':
diff --git a/python/paddle/fluid/tests/unittests/dygraph_to_static/test_variable_trans_func.py b/python/paddle/fluid/tests/unittests/dygraph_to_static/test_variable_trans_func.py
index 403b8f56a18d04fb35cdf0f27e0a30e808f4cd99..9f677d765f9ab26ec37b02feebe806799d362576 100644
--- a/python/paddle/fluid/tests/unittests/dygraph_to_static/test_variable_trans_func.py
+++ b/python/paddle/fluid/tests/unittests/dygraph_to_static/test_variable_trans_func.py
@@ -15,7 +15,6 @@
 from __future__ import print_function
 
 import gast
-import six
 import unittest
 
 import numpy as np
@@ -58,18 +57,9 @@ class TestVariableTransFunc(unittest.TestCase):
         source = "b = paddle.fluid.layers.fill_constant(shape=[1], dtype='bool', value=True)"
         self.assertEqual(ast_to_source_code(node).strip(), source)
 
-        if six.PY2:
-            node = create_fill_constant_node("c", 214)
-            source = "c = paddle.fluid.layers.fill_constant(shape=[1], dtype='int32', value=214)"
-            self.assertEqual(ast_to_source_code(node).strip(), source)
-
-            node = create_fill_constant_node("d", long(10086))
-            source = "d = paddle.fluid.layers.fill_constant(shape=[1], dtype='int64', value=10086)"
-            self.assertEqual(ast_to_source_code(node).strip(), source)
-        else:
-            node = create_fill_constant_node("c", 4293)
-            source = "c = paddle.fluid.layers.fill_constant(shape=[1], dtype='int64', value=4293)"
-            self.assertEqual(ast_to_source_code(node).strip(), source)
+        node = create_fill_constant_node("c", 4293)
+        source = "c = paddle.fluid.layers.fill_constant(shape=[1], dtype='int64', value=4293)"
+        self.assertEqual(ast_to_source_code(node).strip(), source)
 
         self.assertIsNone(create_fill_constant_node("e", None))
         self.assertIsNone(create_fill_constant_node("e", []))
diff --git a/python/paddle/fluid/tests/unittests/npu/test_collective_base_npu.py b/python/paddle/fluid/tests/unittests/npu/test_collective_base_npu.py
index ba2b6329a2564e31098f8994f2e2d4ef192f01f9..b871256acd4db77e71433f9a8e750593affc7802 100644
--- a/python/paddle/fluid/tests/unittests/npu/test_collective_base_npu.py
+++ b/python/paddle/fluid/tests/unittests/npu/test_collective_base_npu.py
@@ -18,14 +18,12 @@ import unittest
 import time
 import argparse
 import os
-import six
 import sys
 import subprocess
 import traceback
 import functools
 import pickle
 from contextlib import closing
-from six import string_types
 import paddle.fluid as fluid
 import paddle.fluid.unique_name as nameGen
 from paddle.fluid import core
@@ -113,10 +111,7 @@ class TestCollectiveRunnerBase(object):
         out = exe.run(train_prog,
                       feed={'tindata': indata},
                       fetch_list=[result.name])
-        if six.PY2:
-            print(pickle.dumps(out))
-        else:
-            sys.stdout.buffer.write(pickle.dumps(out))
+        sys.stdout.buffer.write(pickle.dumps(out))
 
 
 def runtime_main(test_class, col_type, sub_type):
diff --git a/python/paddle/fluid/tests/unittests/test_collective_api_base.py b/python/paddle/fluid/tests/unittests/test_collective_api_base.py
index 81d246d35b8bbacc2950c4fa80c7e46950c40666..6868fb4c7499e92909aaa855849a9380949eae59 100644
--- a/python/paddle/fluid/tests/unittests/test_collective_api_base.py
+++ b/python/paddle/fluid/tests/unittests/test_collective_api_base.py
@@ -18,14 +18,12 @@ import unittest
 import time
 import argparse
 import os
-import six
 import sys
 import subprocess
 import traceback
 import functools
 import pickle
 from contextlib import closing
-from six import string_types
 import paddle
 import paddle.fluid as fluid
 import paddle.fluid.unique_name as nameGen
@@ -69,10 +67,7 @@ class TestCollectiveAPIRunnerBase(object):
         else:
             out = self.get_model(train_prog, startup_prog, rank, indata)
             #print(out, sys.stderr)
-        if six.PY2:
-            print(pickle.dumps(out))
-        else:
-            sys.stdout.buffer.write(pickle.dumps(out))
+        sys.stdout.buffer.write(pickle.dumps(out))
 
 
 def runtime_main(test_class, col_type):
diff --git a/python/paddle/fluid/tests/unittests/test_collective_base.py b/python/paddle/fluid/tests/unittests/test_collective_base.py
index 697e8d32d67a8809ab8047ee89e6aa412397962e..0c278f96dd555f5d5eee4e1a2d60edf3c356d2aa 100644
--- a/python/paddle/fluid/tests/unittests/test_collective_base.py
+++ b/python/paddle/fluid/tests/unittests/test_collective_base.py
@@ -18,14 +18,12 @@ import unittest
 import time
 import argparse
 import os
-import six
 import sys
 import subprocess
 import traceback
 import functools
 import pickle
 from contextlib import closing
-from six import string_types
 import paddle.fluid as fluid
 import paddle.fluid.unique_name as nameGen
 from paddle.fluid import core
@@ -37,7 +35,6 @@ class TestCollectiveRunnerBase(object):
             "get model should be implemented by child class.")
 
     def wait_server_ready(self, endpoints):
-        assert not isinstance(endpoints, string_types)
         while True:
             all_ok = True
             not_ready_endpoints = []
@@ -115,10 +112,7 @@ class TestCollectiveRunnerBase(object):
         out = exe.run(train_prog,
                       feed={'tindata': indata},
                       fetch_list=[result.name])
-        if six.PY2:
-            print(pickle.dumps(out))
-        else:
-            sys.stdout.buffer.write(pickle.dumps(out))
+        sys.stdout.buffer.write(pickle.dumps(out))
 
 
 def runtime_main(test_class, col_type, sub_type):
diff --git a/python/paddle/fluid/tests/unittests/test_compat.py b/python/paddle/fluid/tests/unittests/test_compat.py
index 0c85e85d06fa07e136b54a184ae69e6e8290149f..7f26582889de6c6f7b1b1b9841bc41ed61b9fd36 100644
--- a/python/paddle/fluid/tests/unittests/test_compat.py
+++ b/python/paddle/fluid/tests/unittests/test_compat.py
@@ -16,465 +16,230 @@ from __future__ import print_function
 
 import unittest
 import paddle.compat as cpt
-import six
 
 
 class TestCompatible(unittest.TestCase):
     def test_type(self):
-        if six.PY2:
-            self.assertEqual(cpt.int_type, int)
-            self.assertEqual(cpt.long_type, long)
-        else:
-            self.assertEqual(cpt.int_type, int)
-            self.assertEqual(cpt.long_type, int)
+        self.assertEqual(cpt.int_type, int)
+        self.assertEqual(cpt.long_type, int)
 
     def test_to_text(self):
-        # Only support python2.x and python3.x now
-        self.assertTrue(six.PY2 | six.PY3)
-
-        if six.PY2:
-            # check None
-            self.assertIsNone(cpt.to_text(None))
-
-            # check all string related types
-            self.assertTrue(isinstance(cpt.to_text(str("")), unicode))
-            self.assertTrue(isinstance(cpt.to_text(str("123")), unicode))
-            self.assertTrue(isinstance(cpt.to_text(b""), unicode))
-            self.assertTrue(isinstance(cpt.to_text(b""), unicode))
-            self.assertTrue(isinstance(cpt.to_text(u""), unicode))
-            self.assertTrue(isinstance(cpt.to_text(u""), unicode))
-
-            self.assertEqual(u"", cpt.to_text(str("")))
-            self.assertEqual(u"123", cpt.to_text(str("123")))
-            self.assertEqual(u"", cpt.to_text(b""))
-            self.assertEqual(u"123", cpt.to_text(b"123"))
-            self.assertEqual(u"", cpt.to_text(u""))
-            self.assertEqual(u"123", cpt.to_text(u"123"))
-
-            # check list types, not inplace
-            l = [""]
-            l2 = cpt.to_text(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([u""], l2)
-            l = ["", "123"]
-            l2 = cpt.to_text(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([u"", u"123"], l2)
-            l = ["", b'123', u"321"]
-            l2 = cpt.to_text(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([u"", u"123", u"321"], l2)
-            for i in l2:
-                self.assertTrue(isinstance(i, unicode))
-
-            # check list types, inplace
-            l = [""]
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([u""], l2)
-            l = ["", "123"]
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([u"", u"123"], l2)
-            l = ["", b"123", u"321"]
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([u"", u"123", u"321"], l2)
-
-            # check set types, not inplace
-            l = set("")
-            l2 = cpt.to_text(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(u""), l2)
-            l = set([b"", b"123"])
-            l2 = cpt.to_text(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([u"", u"123"]), l2)
-            l = set(["", b"123", u"321"])
-            l2 = cpt.to_text(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([u"", u"123", u"321"]), l2)
-            for i in l2:
-                self.assertTrue(isinstance(i, unicode))
-
-            # check set types, inplace
-            l = set("")
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(u""), l2)
-            l = set([b"", b"123"])
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([u"", u"123"]), l2)
-            l = set(["", b"123", u"321"])
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([u"", u"123", u"321"]), l2)
-
-            # check dict types, not inplace
-            l = {"": ""}
-            l2 = cpt.to_text(l, inplace=False)
-            self.assertTrue(isinstance(l2, dict))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual({"": ""}, l2)
-
-            # check dict types, inplace
-            l = {"": ""}
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, dict))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual({"": ""}, l2)
-
-        elif six.PY3:
-            self.assertIsNone(cpt.to_text(None))
-
-            self.assertTrue(isinstance(cpt.to_text(str("")), str))
-            self.assertTrue(isinstance(cpt.to_text(str("123")), str))
-            self.assertTrue(isinstance(cpt.to_text(b""), str))
-            self.assertTrue(isinstance(cpt.to_text(b""), str))
-            self.assertTrue(isinstance(cpt.to_text(u""), str))
-            self.assertTrue(isinstance(cpt.to_text(u""), str))
-
-            self.assertEqual("", cpt.to_text(str("")))
-            self.assertEqual("123", cpt.to_text(str("123")))
-            self.assertEqual("", cpt.to_text(b""))
-            self.assertEqual("123", cpt.to_text(b"123"))
-            self.assertEqual("", cpt.to_text(u""))
-            self.assertEqual("123", cpt.to_text(u"123"))
-
-            # check list types, not inplace
-            l = [""]
-            l2 = cpt.to_text(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([""], l2)
-            l = ["", "123"]
-            l2 = cpt.to_text(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(["", "123"], l2)
-            l = ["", b"123", u"321"]
-            l2 = cpt.to_text(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual(["", "123", "321"], l2)
-
-            # check list types, inplace
-            l = [""]
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([""], l2)
-            l = ["", b"123"]
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(["", "123"], l2)
-            l = ["", b"123", u"321"]
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(["", "123", "321"], l2)
-            for i in l2:
-                self.assertTrue(isinstance(i, str))
-
-            # check set types, not inplace
-            l = set("")
-            l2 = cpt.to_text(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(""), l2)
-            l = set([b"", b"123"])
-            l2 = cpt.to_text(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual(set(["", "123"]), l2)
-            l = set(["", b"123", u"321"])
-            l2 = cpt.to_text(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual(set(["", "123", "321"]), l2)
-
-            # check set types, inplace
-            l = set("")
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(""), l2)
-            l = set([b"", b"123"])
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(["", "123"]), l2)
-            l = set(["", b"123", u"321"])
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(["", "123", "321"]), l2)
-            for i in l2:
-                self.assertTrue(isinstance(i, str))
-
-            # check dict types, not inplace
-            l = {"": ""}
-            l2 = cpt.to_text(l, inplace=False)
-            self.assertTrue(isinstance(l2, dict))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual({"": ""}, l2)
-
-            # check dict types, inplace
-            l = {"": ""}
-            l2 = cpt.to_text(l, inplace=True)
-            self.assertTrue(isinstance(l2, dict))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual({"": ""}, l2)
+        self.assertIsNone(cpt.to_text(None))
+
+        self.assertTrue(isinstance(cpt.to_text(str("")), str))
+        self.assertTrue(isinstance(cpt.to_text(str("123")), str))
+        self.assertTrue(isinstance(cpt.to_text(b""), str))
+        self.assertTrue(isinstance(cpt.to_text(b""), str))
+        self.assertTrue(isinstance(cpt.to_text(u""), str))
+        self.assertTrue(isinstance(cpt.to_text(u""), str))
+
+        self.assertEqual("", cpt.to_text(str("")))
+        self.assertEqual("123", cpt.to_text(str("123")))
+        self.assertEqual("", cpt.to_text(b""))
+        self.assertEqual("123", cpt.to_text(b"123"))
+        self.assertEqual("", cpt.to_text(u""))
+        self.assertEqual("123", cpt.to_text(u"123"))
+
+        # check list types, not inplace
+        l = [""]
+        l2 = cpt.to_text(l)
+        self.assertTrue(isinstance(l2, list))
+        self.assertFalse(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual([""], l2)
+        l = ["", "123"]
+        l2 = cpt.to_text(l)
+        self.assertTrue(isinstance(l2, list))
+        self.assertFalse(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(["", "123"], l2)
+        l = ["", b"123", u"321"]
+        l2 = cpt.to_text(l)
+        self.assertTrue(isinstance(l2, list))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual(["", "123", "321"], l2)
+
+        # check list types, inplace
+        l = [""]
+        l2 = cpt.to_text(l, inplace=True)
+        self.assertTrue(isinstance(l2, list))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual([""], l2)
+        l = ["", b"123"]
+        l2 = cpt.to_text(l, inplace=True)
+        self.assertTrue(isinstance(l2, list))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(["", "123"], l2)
+        l = ["", b"123", u"321"]
+        l2 = cpt.to_text(l, inplace=True)
+        self.assertTrue(isinstance(l2, list))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(["", "123", "321"], l2)
+        for i in l2:
+            self.assertTrue(isinstance(i, str))
+
+        # check set types, not inplace
+        l = set("")
+        l2 = cpt.to_text(l, inplace=False)
+        self.assertTrue(isinstance(l2, set))
+        self.assertFalse(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(set(""), l2)
+        l = set([b"", b"123"])
+        l2 = cpt.to_text(l, inplace=False)
+        self.assertTrue(isinstance(l2, set))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual(set(["", "123"]), l2)
+        l = set(["", b"123", u"321"])
+        l2 = cpt.to_text(l, inplace=False)
+        self.assertTrue(isinstance(l2, set))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual(set(["", "123", "321"]), l2)
+
+        # check set types, inplace
+        l = set("")
+        l2 = cpt.to_text(l, inplace=True)
+        self.assertTrue(isinstance(l2, set))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(set(""), l2)
+        l = set([b"", b"123"])
+        l2 = cpt.to_text(l, inplace=True)
+        self.assertTrue(isinstance(l2, set))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(set(["", "123"]), l2)
+        l = set(["", b"123", u"321"])
+        l2 = cpt.to_text(l, inplace=True)
+        self.assertTrue(isinstance(l2, set))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(set(["", "123", "321"]), l2)
+        for i in l2:
+            self.assertTrue(isinstance(i, str))
+
+        # check dict types, not inplace
+        l = {"": ""}
+        l2 = cpt.to_text(l, inplace=False)
+        self.assertTrue(isinstance(l2, dict))
+        self.assertFalse(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual({"": ""}, l2)
+
+        # check dict types, inplace
+        l = {"": ""}
+        l2 = cpt.to_text(l, inplace=True)
+        self.assertTrue(isinstance(l2, dict))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual({"": ""}, l2)
 
     def test_to_bytes(self):
-        # Only support python2.x and python3.x now
-        self.assertTrue(six.PY2 | six.PY3)
-
-        if six.PY2:
-            # check None
-            self.assertIsNone(cpt.to_bytes(None))
-
-            # check all string related types
-            self.assertTrue(isinstance(cpt.to_bytes(str("")), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(str("123")), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(b""), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(b""), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(u""), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(u""), bytes))
-
-            self.assertEqual(b"", cpt.to_bytes(str("")))
-            self.assertEqual(b"123", cpt.to_bytes(str("123")))
-            self.assertEqual(b"", cpt.to_bytes(b""))
-            self.assertEqual(b"123", cpt.to_bytes(b"123"))
-            self.assertEqual(b"", cpt.to_bytes(u""))
-            self.assertEqual(b"123", cpt.to_bytes(u"123"))
-
-            # check list types, not inplace
-            l = [""]
-            l2 = cpt.to_bytes(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b""], l2)
-            l = ["", "123"]
-            l2 = cpt.to_bytes(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b"", b"123"], l2)
-            l = ["", b'123', u"321"]
-            l2 = cpt.to_bytes(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b"", b"123", b"321"], l2)
-            for i in l2:
-                self.assertTrue(isinstance(i, bytes))
-
-            # check list types, inplace
-            l = [""]
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b""], l2)
-            l = ["", "123"]
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b"", b"123"], l2)
-            l = ["", b"123", u"321"]
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b"", b"123", b"321"], l2)
-
-            # check set types, not inplace
-            l = set("")
-            l2 = cpt.to_bytes(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(b""), l2)
-            l = set([b"", b"123"])
-            l2 = cpt.to_bytes(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([b"", b"123"]), l2)
-            l = set(["", b"123", u"321"])
-            l2 = cpt.to_bytes(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([b"", b"123", b"321"]), l2)
-            for i in l2:
-                self.assertTrue(isinstance(i, bytes))
-
-            # check set types, inplace
-            l = set("")
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(b""), l2)
-            l = set([b"", b"123"])
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([b"", b"123"]), l2)
-            l = set(["", b"123", u"321"])
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([b"", b"123", b"321"]), l2)
-
-        elif six.PY3:
-            self.assertIsNone(cpt.to_bytes(None))
-
-            self.assertTrue(isinstance(cpt.to_bytes(str("")), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(str("123")), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(b""), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(b""), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(u""), bytes))
-            self.assertTrue(isinstance(cpt.to_bytes(u""), bytes))
-
-            self.assertEqual(b"", cpt.to_bytes(str("")))
-            self.assertEqual(b"123", cpt.to_bytes(str("123")))
-            self.assertEqual(b"", cpt.to_bytes(b""))
-            self.assertEqual(b"123", cpt.to_bytes(b"123"))
-            self.assertEqual(b"", cpt.to_bytes(u""))
-            self.assertEqual(b"123", cpt.to_bytes(u"123"))
-
-            # check list types, not inplace
-            l = [""]
-            l2 = cpt.to_bytes(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual([b""], l2)
-            l = ["", "123"]
-            l2 = cpt.to_bytes(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual([b"", b"123"], l2)
-            l = ["", b"123", u"321"]
-            l2 = cpt.to_bytes(l)
-            self.assertTrue(isinstance(l2, list))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual([b"", b"123", b"321"], l2)
-
-            # check list types, inplace
-            l = [""]
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b""], l2)
-            l = ["", b"123"]
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b"", b"123"], l2)
-            l = ["", b"123", u"321"]
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, list))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual([b"", b"123", b"321"], l2)
-            for i in l2:
-                self.assertTrue(isinstance(i, bytes))
-
-            # check set types, not inplace
-            l = set([""])
-            l2 = cpt.to_bytes(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual(set([b""]), l2)
-            l = set([u"", u"123"])
-            l2 = cpt.to_bytes(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual(set([b"", b"123"]), l2)
-            l = set(["", b"123", u"321"])
-            l2 = cpt.to_bytes(l, inplace=False)
-            self.assertTrue(isinstance(l2, set))
-            self.assertFalse(l is l2)
-            self.assertNotEqual(l, l2)
-            self.assertEqual(set([b"", b"123", b"321"]), l2)
-
-            # check set types, inplace
-            l = set("")
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set(b""), l2)
-            l = set([u"", u"123"])
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([b"", b"123"]), l2)
-            l = set(["", b"123", u"321"])
-            l2 = cpt.to_bytes(l, inplace=True)
-            self.assertTrue(isinstance(l2, set))
-            self.assertTrue(l is l2)
-            self.assertEqual(l, l2)
-            self.assertEqual(set([b"", b"123", b"321"]), l2)
-            for i in l2:
-                self.assertTrue(isinstance(i, bytes))
+        self.assertIsNone(cpt.to_bytes(None))
+
+        self.assertTrue(isinstance(cpt.to_bytes(str("")), bytes))
+        self.assertTrue(isinstance(cpt.to_bytes(str("123")), bytes))
+        self.assertTrue(isinstance(cpt.to_bytes(b""), bytes))
+        self.assertTrue(isinstance(cpt.to_bytes(b""), bytes))
+        self.assertTrue(isinstance(cpt.to_bytes(u""), bytes))
+        self.assertTrue(isinstance(cpt.to_bytes(u""), bytes))
+
+        self.assertEqual(b"", cpt.to_bytes(str("")))
+        self.assertEqual(b"123", cpt.to_bytes(str("123")))
+        self.assertEqual(b"", cpt.to_bytes(b""))
+        self.assertEqual(b"123", cpt.to_bytes(b"123"))
+        self.assertEqual(b"", cpt.to_bytes(u""))
+        self.assertEqual(b"123", cpt.to_bytes(u"123"))
+
+        # check list types, not inplace
+        l = [""]
+        l2 = cpt.to_bytes(l)
+        self.assertTrue(isinstance(l2, list))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual([b""], l2)
+        l = ["", "123"]
+        l2 = cpt.to_bytes(l)
+        self.assertTrue(isinstance(l2, list))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual([b"", b"123"], l2)
+        l = ["", b"123", u"321"]
+        l2 = cpt.to_bytes(l)
+        self.assertTrue(isinstance(l2, list))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual([b"", b"123", b"321"], l2)
+
+        # check list types, inplace
+        l = [""]
+        l2 = cpt.to_bytes(l, inplace=True)
+        self.assertTrue(isinstance(l2, list))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual([b""], l2)
+        l = ["", b"123"]
+        l2 = cpt.to_bytes(l, inplace=True)
+        self.assertTrue(isinstance(l2, list))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual([b"", b"123"], l2)
+        l = ["", b"123", u"321"]
+        l2 = cpt.to_bytes(l, inplace=True)
+        self.assertTrue(isinstance(l2, list))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual([b"", b"123", b"321"], l2)
+        for i in l2:
+            self.assertTrue(isinstance(i, bytes))
+
+        # check set types, not inplace
+        l = set([""])
+        l2 = cpt.to_bytes(l, inplace=False)
+        self.assertTrue(isinstance(l2, set))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual(set([b""]), l2)
+        l = set([u"", u"123"])
+        l2 = cpt.to_bytes(l, inplace=False)
+        self.assertTrue(isinstance(l2, set))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual(set([b"", b"123"]), l2)
+        l = set(["", b"123", u"321"])
+        l2 = cpt.to_bytes(l, inplace=False)
+        self.assertTrue(isinstance(l2, set))
+        self.assertFalse(l is l2)
+        self.assertNotEqual(l, l2)
+        self.assertEqual(set([b"", b"123", b"321"]), l2)
+
+        # check set types, inplace
+        l = set("")
+        l2 = cpt.to_bytes(l, inplace=True)
+        self.assertTrue(isinstance(l2, set))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(set(b""), l2)
+        l = set([u"", u"123"])
+        l2 = cpt.to_bytes(l, inplace=True)
+        self.assertTrue(isinstance(l2, set))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(set([b"", b"123"]), l2)
+        l = set(["", b"123", u"321"])
+        l2 = cpt.to_bytes(l, inplace=True)
+        self.assertTrue(isinstance(l2, set))
+        self.assertTrue(l is l2)
+        self.assertEqual(l, l2)
+        self.assertEqual(set([b"", b"123", b"321"]), l2)
+        for i in l2:
+            self.assertTrue(isinstance(i, bytes))
 
     def test_round(self):
         self.assertEqual(3.0, cpt.round(3.4))
@@ -500,37 +265,17 @@ class TestCompatible(unittest.TestCase):
     def test_get_exception_message(self):
         exception_message = "test_message"
         self.assertRaises(AssertionError, cpt.get_exception_message, None)
-        if six.PY2:
-            self.assertRaises(AttributeError, cpt.get_exception_message,
-                              exception_message)
-            try:
-                raise RuntimeError(exception_message)
-            except Exception as e:
-                self.assertEqual(exception_message,
-                                 cpt.get_exception_message(e))
-                self.assertIsNotNone(e)
-
-            try:
-                raise Exception(exception_message)
-            except Exception as e:
-                self.assertEqual(exception_message,
-                                 cpt.get_exception_message(e))
-                self.assertIsNotNone(e)
-
-        if six.PY3:
-            try:
-                raise RuntimeError(exception_message)
-            except Exception as e:
-                self.assertEqual(exception_message,
-                                 cpt.get_exception_message(e))
-                self.assertIsNotNone(e)
-
-            try:
-                raise Exception(exception_message)
-            except Exception as e:
-                self.assertEqual(exception_message,
-                                 cpt.get_exception_message(e))
-                self.assertIsNotNone(e)
+        try:
+            raise RuntimeError(exception_message)
+        except Exception as e:
+            self.assertEqual(exception_message, cpt.get_exception_message(e))
+            self.assertIsNotNone(e)
+
+        try:
+            raise Exception(exception_message)
+        except Exception as e:
+            self.assertEqual(exception_message, cpt.get_exception_message(e))
+            self.assertIsNotNone(e)
 
 
 if __name__ == "__main__":
diff --git a/python/paddle/fluid/tests/unittests/test_dist_base.py b/python/paddle/fluid/tests/unittests/test_dist_base.py
index 78b06bd5333d79b4aa90d00f1c1f16a399e61929..2c3dc7eb4b7de8e4eb932cb1ea30a884cbd573ed 100755
--- a/python/paddle/fluid/tests/unittests/test_dist_base.py
+++ b/python/paddle/fluid/tests/unittests/test_dist_base.py
@@ -44,19 +44,13 @@ DIST_UT_PORT = 0
 
 
 def print_to_out(out_losses):
-    if six.PY2:
-        print(pickle.dumps(out_losses))
-    else:
-        sys.stdout.buffer.write(pickle.dumps(out_losses))
+    sys.stdout.buffer.write(pickle.dumps(out_losses))
 
 
 def print_to_err(class_name, log_str):
     localtime = time.asctime(time.localtime(time.time()))
     print_str = localtime + "\t" + class_name + "\t" + log_str
-    if six.PY2:
-        sys.stderr.write(pickle.dumps(print_str))
-    else:
-        sys.stderr.buffer.write(pickle.dumps(print_str))
+    sys.stderr.buffer.write(pickle.dumps(print_str))
 
 
 def eprint(*args, **kwargs):
@@ -151,10 +145,7 @@ class TestDistRunnerBase(object):
             print_to_err(type(self).__name__, "run step %d finished" % i)
         print_to_err(type(self).__name__, "trainer run finished")
 
-        if six.PY2:
-            print(pickle.dumps(out_losses))
-        else:
-            sys.stdout.buffer.write(pickle.dumps(out_losses))
+        sys.stdout.buffer.write(pickle.dumps(out_losses))
 
         if args.save_model:
             model_save_dir = "/tmp"
@@ -251,10 +242,7 @@ class TestDistRunnerBase(object):
         print_to_err(type(self).__name__, "trainer run finished")
         print_to_err(type(self).__name__, "dist losses: {}".format(out_losses))
 
-        if six.PY2:
-            print(pickle.dumps(out_losses))
-        else:
-            sys.stdout.buffer.write(pickle.dumps(out_losses))
+        sys.stdout.buffer.write(pickle.dumps(out_losses))
 
     def run_use_fleet_api_trainer(self, args):
         assert args.update_method == "nccl2" or "bkcl"
@@ -338,10 +326,7 @@ class TestDistRunnerBase(object):
             print_to_err(type(self).__name__, "run step %d finished" % i)
         print_to_err(type(self).__name__, "trainer run finished")
 
-        if six.PY2:
-            print(pickle.dumps(out_losses))
-        else:
-            sys.stdout.buffer.write(pickle.dumps(out_losses))
+        sys.stdout.buffer.write(pickle.dumps(out_losses))
 
         if args.save_model:
             model_save_dir = "/tmp"
diff --git a/python/paddle/fluid/tests/unittests/test_math_op_patch_var_base.py b/python/paddle/fluid/tests/unittests/test_math_op_patch_var_base.py
index 4ad6261293d260e911806ef2f0b7771e1dadad66..7de6148fe73da29fb3b2a44ba9fd57b99cd76b95 100644
--- a/python/paddle/fluid/tests/unittests/test_math_op_patch_var_base.py
+++ b/python/paddle/fluid/tests/unittests/test_math_op_patch_var_base.py
@@ -18,7 +18,6 @@ import unittest
 import paddle
 import paddle.fluid as fluid
 import numpy as np
-import six
 import inspect
 
 
@@ -241,10 +240,7 @@ class TestMathOpPatchesVarBase(unittest.TestCase):
             a = fluid.dygraph.to_variable(np.array([100.1]))
             self.assertTrue(float(a) == 100.1)
             self.assertTrue(int(a) == 100)
-            if six.PY2:
-                self.assertTrue(long(a) == 100)
-            else:
-                self.assertTrue(int(a) == 100)
+            self.assertTrue(int(a) == 100)
 
     def test_len(self):
         a_np = np.random.uniform(-1, 1, self.shape).astype(self.dtype)
diff --git a/python/paddle/fluid/tests/unittests/test_paddle_save_load.py b/python/paddle/fluid/tests/unittests/test_paddle_save_load.py
index fe8692a38814e92bba93fb82f103a77b13cd9153..77aa4ae36b3acec93aae463a8fd11035a9b7c274 100644
--- a/python/paddle/fluid/tests/unittests/test_paddle_save_load.py
+++ b/python/paddle/fluid/tests/unittests/test_paddle_save_load.py
@@ -18,7 +18,6 @@ import unittest
 import numpy as np
 import os
 import sys
-import six
 from io import BytesIO
 
 import paddle
@@ -38,10 +37,7 @@ SEED = 10
 IMAGE_SIZE = 784
 CLASS_NUM = 10
 
-if six.PY2:
-    LARGE_PARAM = 2**2
-else:
-    LARGE_PARAM = 2**26
+LARGE_PARAM = 2**26
 
 
 def random_batch_reader():
@@ -105,10 +101,7 @@ class TestSaveLoadLargeParameters(unittest.TestCase):
 
         path = os.path.join("test_paddle_save_load_large_param_save",
                             "layer.pdparams")
-        if six.PY2:
-            protocol = 2
-        else:
-            protocol = 4
+        protocol = 4
         paddle.save(save_dict, path, protocol=protocol)
         dict_load = paddle.load(path)
         # compare results before and after saving
@@ -926,9 +919,6 @@ class TestSaveLoadProgram(unittest.TestCase):
 
 class TestSaveLoadLayer(unittest.TestCase):
     def test_save_load_layer(self):
-        if six.PY2:
-            return
-
         paddle.disable_static()
         inps = paddle.randn([1, IMAGE_SIZE], dtype='float32')
         layer1 = LinearNet()
diff --git a/python/paddle/fluid/tests/unittests/test_static_save_load_large.py b/python/paddle/fluid/tests/unittests/test_static_save_load_large.py
index c5dc98af5c8f6d0dded8700bbdcdbbc325989066..389fc259b5549b38a535f1e277a48fb374e91085 100644
--- a/python/paddle/fluid/tests/unittests/test_static_save_load_large.py
+++ b/python/paddle/fluid/tests/unittests/test_static_save_load_large.py
@@ -21,15 +21,10 @@ import paddle.fluid.framework as framework
 from test_imperative_base import new_program_scope
 
 import numpy as np
-import six
 import pickle
 import os
 
-# Python2.x no longer supports saving and loading large parameters.
-if six.PY2:
-    LARGE_PARAM = 2
-else:
-    LARGE_PARAM = 2**26
+LARGE_PARAM = 2**26
 
 
 class TestStaticSaveLoadLargeParameters(unittest.TestCase):
@@ -59,10 +54,7 @@ class TestStaticSaveLoadLargeParameters(unittest.TestCase):
 
             path = os.path.join("test_static_save_load_large_param",
                                 "static_save")
-            if six.PY2:
-                protocol = 2
-            else:
-                protocol = 4
+            protocol = 4
             paddle.fluid.save(prog, path, pickle_protocol=protocol)
             # set var to zero
             for var in prog.list_vars():
diff --git a/python/paddle/fluid/tests/unittests/test_traced_layer_err_msg.py b/python/paddle/fluid/tests/unittests/test_traced_layer_err_msg.py
index 85d830485e23f16487bebc9cc033fae2951ed7f8..3b9fbd69e9d0a699a510cc7b2897786d123f5c2d 100644
--- a/python/paddle/fluid/tests/unittests/test_traced_layer_err_msg.py
+++ b/python/paddle/fluid/tests/unittests/test_traced_layer_err_msg.py
@@ -15,7 +15,6 @@
 import numpy as np
 import paddle
 import paddle.fluid as fluid
-import six
 import unittest
 import paddle.nn as nn
 import os
@@ -50,10 +49,7 @@ class TestTracedLayerErrMsg(unittest.TestCase):
         self.feature_size = 3
         self.fc_size = 2
         self.layer = self._train_simple_net()
-        if six.PY2:
-            self.type_str = 'type'
-        else:
-            self.type_str = 'class'
+        self.type_str = 'class'
 
     def test_trace_err(self):
         with fluid.dygraph.guard():
diff --git a/python/paddle/fluid/tests/unittests/test_var_base.py b/python/paddle/fluid/tests/unittests/test_var_base.py
index be7b7511155816e13a037ceab67279fe81bd2950..98bc79fc7cb4eea1a4fe15e5387950a02ac973c2 100644
--- a/python/paddle/fluid/tests/unittests/test_var_base.py
+++ b/python/paddle/fluid/tests/unittests/test_var_base.py
@@ -192,7 +192,7 @@ class TestVarBase(unittest.TestCase):
 
                 x = paddle.to_tensor(1, dtype='int64')
                 self.assertEqual(x.item(), 1)
-                self.assertTrue(isinstance(x.item(), long if six.PY2 else int))
+                self.assertTrue(isinstance(x.item(), int))
 
                 x = paddle.to_tensor(True)
                 self.assertEqual(x.item(), True)
diff --git a/python/paddle/framework/io.py b/python/paddle/framework/io.py
index d02d078d547deaeb29b59a21e28c4971ae5b9a2d..61c448e19f22d0802fe3a19641b3942df3a2b7c3 100644
--- a/python/paddle/framework/io.py
+++ b/python/paddle/framework/io.py
@@ -17,14 +17,10 @@ from __future__ import print_function
 import os
 import collections
 import pickle
-import six
 import warnings
 import sys
 import numpy as np
-
-if not six.PY2:
-    import copyreg
-
+import copyreg
 import paddle
 
 # deprecated module import
@@ -296,19 +292,14 @@ def _pickle_save(obj, f, protocol):
         for i in range(0, len(pickle_bytes), max_bytes):
             f.write(pickle_bytes[i:i + max_bytes])
     else:
-        if six.PY2:
-            add_dispatch_table()
-            pickle_bytes = pickle.dump(obj, f, protocol)
-            pop_dispatch_table()
-        else:
-            pickler = pickle.Pickler(f, protocol)
-            pickler.dispatch_table = copyreg.dispatch_table.copy()
+        pickler = pickle.Pickler(f, protocol)
+        pickler.dispatch_table = copyreg.dispatch_table.copy()
 
-            pickler.dispatch_table[core.VarBase] = reduce_varbase
-            pickler.dispatch_table[core.LoDTensor] = reduce_LoDTensor
-            pickler.dispatch_table[ParamBase] = reduce_varbase
-            pickler.dispatch_table.update(dispatch_table_layer)
-            pickler.dump(obj)
+        pickler.dispatch_table[core.VarBase] = reduce_varbase
+        pickler.dispatch_table[core.LoDTensor] = reduce_LoDTensor
+        pickler.dispatch_table[ParamBase] = reduce_varbase
+        pickler.dispatch_table.update(dispatch_table_layer)
+        pickler.dump(obj)
 
 
 def _contain_x(obj, condition_func):
@@ -359,10 +350,7 @@ def _transformed_from_varbase(obj):
     # In paddle2.1 version, VarBase is saved as tuple(tensor.name, tensor.numpy()).
     # When executing paddle.load, use this function to determine whether to restore to VarBase/LoDTensor.
     if isinstance(obj, tuple) and len(obj) == 2:
-        if six.PY2:
-            name_types = (str, unicode)
-        else:
-            name_types = str
+        name_types = str
         if isinstance(obj[0], name_types) and isinstance(obj[1], np.ndarray):
             return True
     return False
@@ -947,10 +935,7 @@ def load(path, **configs):
 
     if _is_memory_buffer(path) or os.path.isfile(path):
         config = _parse_load_config(configs)
-        if six.PY2:
-            exception_type = KeyError
-        else:
-            exception_type = pickle.UnpicklingError
+        exception_type = pickle.UnpicklingError
         try:
             with _open_file_buffer(path, 'rb') as f:
                 # When value of dict is lager than 4GB ,there is a Bug on 'MAC python3'
@@ -959,8 +944,7 @@ def load(path, **configs):
                 ) and sys.platform == 'darwin' and sys.version_info.major == 3:
                     load_result = _pickle_loads_mac(path, f)
                 else:
-                    load_result = pickle.load(f) if six.PY2 else pickle.load(
-                        f, encoding='latin1')
+                    load_result = pickle.load(f, encoding='latin1')
 
                 # TODO(weixin):If `obj` is any object, the judgment condition should be more precise.
                 if isinstance(load_result, dict):
@@ -1021,8 +1005,7 @@ def _legacy_load(path, **configs):
     if os.path.isfile(path) or _is_memory_buffer(path):
         # we think path is file means this file is created by paddle.save
         with _open_file_buffer(path, 'rb') as f:
-            load_result = pickle.load(f) if six.PY2 else pickle.load(
-                f, encoding='latin1')
+            load_result = pickle.load(f, encoding='latin1')
         load_result = _pack_loaded_dict(load_result)
         if not config.keep_name_table and "StructuredToParameterName@@" in load_result:
             del load_result["StructuredToParameterName@@"]
diff --git a/python/paddle/hapi/model.py b/python/paddle/hapi/model.py
index 3cba75fd526910be1fa6f452133fd7bcd1377787..c9b6c0098e282302ba324c1856aa8dbf5ab0294b 100644
--- a/python/paddle/hapi/model.py
+++ b/python/paddle/hapi/model.py
@@ -1296,8 +1296,7 @@ class Model(object):
             if not os.path.exists(path):
                 return
             with open(path, 'rb') as f:
-                return pickle.load(f) if six.PY2 else pickle.load(
-                    f, encoding='latin1')
+                return pickle.load(f, encoding='latin1')
 
         def _check_match(key, param):
             state = param_state.get(key, None)
diff --git a/python/paddle/tensor/manipulation.py b/python/paddle/tensor/manipulation.py
index c3031c41279c3cdb26c8cc740a0a401344b8bf52..1c33d19db4bdd04b747c13b4d844b0ad5ee8ff8b 100644
--- a/python/paddle/tensor/manipulation.py
+++ b/python/paddle/tensor/manipulation.py
@@ -21,7 +21,6 @@ from ..fluid.data_feeder import convert_dtype, check_variable_and_dtype, check_t
 from ..fluid.layers.tensor import fill_constant
 from ..fluid.layers import utils
 import numpy as np
-import six
 # TODO: define functions to manipulate a tensor  
 from ..fluid.layers import cast  # noqa: F401
 from ..fluid.layers import slice  # noqa: F401
@@ -1218,10 +1217,7 @@ def tile(x, repeat_times, name=None):
                 assert len(elem.shape) == 1, (
                     'Elements in repeat_times must be 1-D Tensors or integers.')
             else:
-                if six.PY3:
-                    type_tuple = (int, np.int32, np.int64)
-                elif six.PY2:
-                    type_tuple = (int, long, np.int32, np.int64)
+                type_tuple = (int, np.int32, np.int64)
                 assert isinstance(elem, type_tuple), (
                     'Elements in repeat_times must be 1-D Tensors or integers.')
 
@@ -1357,10 +1353,7 @@ def broadcast_to(x, shape, name=None):
                 assert len(elem.shape) == 1, (
                     'Elements in shape must be 1-D Tensors or integers.')
             else:
-                if six.PY3:
-                    type_tuple = (int, np.int32, np.int64)
-                elif six.PY2:
-                    type_tuple = (int, long, np.int32, np.int64)
+                type_tuple = (int, np.int32, np.int64)
                 assert isinstance(elem, type_tuple), (
                     'Elements in shape must be 1-D Tensors or integers.')
 
@@ -1447,10 +1440,7 @@ def expand(x, shape, name=None):
                 assert len(elem.shape) == 1, (
                     'Elements in shape must be 1-D Tensors or integers.')
             else:
-                if six.PY3:
-                    type_tuple = (int, np.int32, np.int64)
-                elif six.PY2:
-                    type_tuple = (int, long, np.int32, np.int64)
+                type_tuple = (int, np.int32, np.int64)
                 assert isinstance(elem, type_tuple), (
                     'Elements in shape must be 1-D Tensors or integers.')
 
diff --git a/python/paddle/utils/cpp_extension/extension_utils.py b/python/paddle/utils/cpp_extension/extension_utils.py
index 104d979ef6785826277ec61756bc75c617be7e2c..4a9ecb9b78b1d23dad89b80c59ebb55d03a716bb 100644
--- a/python/paddle/utils/cpp_extension/extension_utils.py
+++ b/python/paddle/utils/cpp_extension/extension_utils.py
@@ -14,7 +14,6 @@
 
 import os
 import re
-import six
 import sys
 import json
 import glob
@@ -541,8 +540,7 @@ def find_cuda_home():
             with open(os.devnull, 'w') as devnull:
                 nvcc_path = subprocess.check_output(
                     [which_cmd, 'nvcc'], stderr=devnull)
-                if six.PY3:
-                    nvcc_path = nvcc_path.decode()
+                nvcc_path = nvcc_path.decode()
                 # Multi CUDA, select the first
                 nvcc_path = nvcc_path.split('\r\n')[0]
 
@@ -580,8 +578,7 @@ def find_rocm_home():
             with open(os.devnull, 'w') as devnull:
                 hipcc_path = subprocess.check_output(
                     [which_cmd, 'hipcc'], stderr=devnull)
-                if six.PY3:
-                    hipcc_path = hipcc_path.decode()
+                hipcc_path = hipcc_path.decode()
                 hipcc_path = hipcc_path.rstrip('\r\n')
 
                 # for example: /opt/rocm/bin/hipcc
@@ -652,8 +649,7 @@ def find_clang_cpp_include(compiler='clang'):
     std_v1_includes = None
     try:
         compiler_version = subprocess.check_output([compiler, "--version"])
-        if six.PY3:
-            compiler_version = compiler_version.decode()
+        compiler_version = compiler_version.decode()
         infos = compiler_version.split("\n")
         for info in infos:
             if "InstalledDir" in info:
@@ -895,13 +891,9 @@ def _load_module_from_file(api_file_path, verbose=False):
     # Unique readable module name to place custom api.
     log_v('import module from file: {}'.format(api_file_path), verbose)
     ext_name = "_paddle_cpp_extension_"
-    if six.PY2:
-        import imp
-        module = imp.load_source(ext_name, api_file_path)
-    else:
-        from importlib import machinery
-        loader = machinery.SourceFileLoader(ext_name, api_file_path)
-        module = loader.load_module()
+    from importlib import machinery
+    loader = machinery.SourceFileLoader(ext_name, api_file_path)
+    module = loader.load_module()
 
     return module
 
@@ -1005,8 +997,7 @@ def _jit_compile(file_path, verbose=False):
 
     try:
         py_version = subprocess.check_output([interpreter, '-V'])
-        if six.PY3:
-            py_version = py_version.decode()
+        py_version = py_version.decode()
         log_v("Using Python interpreter: {}, version: {}".format(
             interpreter, py_version.strip()), verbose)
     except Exception:
@@ -1083,8 +1074,7 @@ def check_abi_compatibility(compiler, verbose=False):
     if not IS_WINDOWS:
         cmd_out = subprocess.check_output(
             ['which', compiler], stderr=subprocess.STDOUT)
-        compiler_path = os.path.realpath(cmd_out.decode()
-                                         if six.PY3 else cmd_out).strip()
+        compiler_path = os.path.realpath(cmd_out.decode()).strip()
         # if not found any suitable compiler, raise warning
         if not any(name in compiler_path
                    for name in _expected_compiler_current_platform()):
@@ -1104,18 +1094,16 @@ def check_abi_compatibility(compiler, verbose=False):
             mini_required_version = GCC_MINI_VERSION
             version_info = subprocess.check_output(
                 [compiler, '-dumpfullversion', '-dumpversion'])
-            if six.PY3:
-                version_info = version_info.decode()
+            version_info = version_info.decode()
             version = version_info.strip().split('.')
         elif IS_WINDOWS:
             mini_required_version = MSVC_MINI_VERSION
             compiler_info = subprocess.check_output(
                 compiler, stderr=subprocess.STDOUT)
-            if six.PY3:
-                try:
-                    compiler_info = compiler_info.decode('UTF-8')
-                except UnicodeDecodeError:
-                    compiler_info = compiler_info.decode('gbk')
+            try:
+                compiler_info = compiler_info.decode('UTF-8')
+            except UnicodeDecodeError:
+                compiler_info = compiler_info.decode('gbk')
             match = re.search(r'(\d+)\.(\d+)\.(\d+)', compiler_info.strip())
             if match is not None:
                 version = match.groups()
diff --git a/python/paddle/vision/datasets/cifar.py b/python/paddle/vision/datasets/cifar.py
index a70b0317fc27d93bab5d0fd2fd8163bbfc676406..97ffb239fe7adf6d9482f765d64aaf460926c566 100644
--- a/python/paddle/vision/datasets/cifar.py
+++ b/python/paddle/vision/datasets/cifar.py
@@ -141,10 +141,7 @@ class Cifar10(Dataset):
                      if self.flag in each_item.name)
 
             for name in names:
-                if six.PY2:
-                    batch = pickle.load(f.extractfile(name))
-                else:
-                    batch = pickle.load(f.extractfile(name), encoding='bytes')
+                batch = pickle.load(f.extractfile(name), encoding='bytes')
 
                 data = batch[six.b('data')]
                 labels = batch.get(
diff --git a/tools/count_api_without_core_ops.py b/tools/count_api_without_core_ops.py
index 7af597600e0010eda2ae2a391419f6cb10b33e9b..e84a03d93e9bbfbc21552e97e98ccc706c1f4317 100644
--- a/tools/count_api_without_core_ops.py
+++ b/tools/count_api_without_core_ops.py
@@ -20,7 +20,6 @@ import collections
 import sys
 import pydoc
 import hashlib
-import six
 import functools
 import platform
 
@@ -104,7 +103,7 @@ def visit_member(parent_name, member, func):
 
 
 def is_primitive(instance):
-    int_types = (int, long) if six.PY2 else (int, )
+    int_types = (int, )
     pritimitive_types = int_types + (float, str)
     if isinstance(instance, pritimitive_types):
         return True