diff --git a/demo/mnist/api_train_v2.py b/demo/mnist/api_train_v2.py
new file mode 100644
index 0000000000000000000000000000000000000000..19c11b6de5e0b5eaa63702953e3d437812e609cd
--- /dev/null
+++ b/demo/mnist/api_train_v2.py
@@ -0,0 +1,61 @@
+from paddle.trainer_config_helpers import *
+from paddle.trainer.PyDataProvider2 import dense_vector, integer_value
+import paddle.v2 as paddle_v2
+import numpy
+import mnist_util
+
+
+def train_reader():
+    train_file = './data/raw_data/train'
+    generator = mnist_util.read_from_mnist(train_file)
+    for item in generator:
+        yield item
+
+
+def network_config():
+    imgs = data_layer(name='pixel', size=784)
+    hidden1 = fc_layer(input=imgs, size=200)
+    hidden2 = fc_layer(input=hidden1, size=200)
+    inference = fc_layer(input=hidden2, size=10, act=SoftmaxActivation())
+    cost = classification_cost(
+        input=inference, label=data_layer(
+            name='label', size=10))
+    outputs(cost)
+
+
+def event_handler(event):
+    if isinstance(event, paddle_v2.trainer.CompleteTrainOneBatch):
+        print "Pass %d, Batch %d, Cost %f" % (event.pass_id, event.batch_id,
+                                              event.cost)
+    else:
+        pass
+
+
+def main():
+    paddle_v2.init(use_gpu=False, trainer_count=1)
+    model_config = parse_network_config(network_config)
+    pool = paddle_v2.parameters.create(model_config)
+    for param_name in pool.get_names():
+        array = pool.get_parameter(param_name)
+        array[:] = numpy.random.uniform(low=-1.0, high=1.0, size=array.shape)
+
+    trainer = paddle_v2.trainer.SGDTrainer(
+        update_equation=paddle_v2.optimizer.Adam(
+            learning_rate=1e-4,
+            model_average=ModelAverage(average_window=0.5),
+            regularization=L2Regularization(rate=0.5)))
+
+    trainer.train(train_data_reader=train_reader,
+                  topology=model_config,
+                  parameters=pool,
+                  event_handler=event_handler,
+                  batch_size=32,  # batch size should be refactor in Data reader
+                  data_types={  # data_types will be removed, It should be in
+                      # network topology
+                      'pixel': dense_vector(784),
+                      'label': integer_value(10)
+                  })
+
+
+if __name__ == '__main__':
+    main()
diff --git a/python/paddle/v2/__init__.py b/python/paddle/v2/__init__.py
index b2ea87b086101d71e89c33ce7c1f4eb21afade5a..f50c36ce64995bbbbd6fe96b123bdcb711fd5248 100644
--- a/python/paddle/v2/__init__.py
+++ b/python/paddle/v2/__init__.py
@@ -11,7 +11,17 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
 import optimizer
+import parameters
+import py_paddle.swig_paddle as api
+import trainer
+
+__all__ = ['optimizer', 'parameters', 'init', 'trainer']
+
+
+def init(**kwargs):
+    args = []
+    for key in kwargs.keys():
+        args.append('--%s=%s' % (key, str(kwargs[key])))
 
-__all__ = ['optimizer']
+    api.initPaddle(*args)
diff --git a/python/paddle/v2/parameters.py b/python/paddle/v2/parameters.py
new file mode 100644
index 0000000000000000000000000000000000000000..892c68a38bd70679d0a4f58f5149b09c1d5b41cd
--- /dev/null
+++ b/python/paddle/v2/parameters.py
@@ -0,0 +1,111 @@
+import numpy as np
+
+from paddle.proto.ModelConfig_pb2 import ModelConfig
+from paddle.proto.ParameterConfig_pb2 import ParameterConfig
+
+__all__ = ['IParameterPool', 'create', 'ParameterFlag']
+
+
+class ParameterFlag(object):
+    """
+    The flag for IParameterPool.get_parameter. If writeable, operation on return
+    numpy array will also apply to Paddle parameter. But it will be slower in
+    GPU mode.
+    """
+    READ_ONLY = 0x01
+    WRITE_ONLY = 0x02
+    READ_WRITE = READ_ONLY | WRITE_ONLY
+
+
+class IParameterPool(object):
+    """
+    Interface of Parameter Pool. The parameter pool is a dictionary of
+    parameters. User can modify parameter or customize parameter value
+    by `get_parameter`.
+
+    ..  code-block:: python
+
+        pool = paddle.parameters.create(topo1, topo2)
+
+        embedding = pool.get_parameter("embedding")
+        assert isinstance(embedding, numpy.ndarray)
+        print embedding[1:]
+    """
+
+    def get_parameter(self, name, flag=ParameterFlag.READ_WRITE):
+        """
+        Get a parameter by name.
+
+        :param name: parameter name.
+        :type name: basestring
+        :param flag: the flag for return value. readable or writable.
+        :type flag: int
+        :return: The parameter value
+        :rtype: np.ndarray
+        """
+        raise NotImplementedError()
+
+    def get_names(self):
+        """
+        Get all parameter names
+        :return: all parameter names
+        :rtype: list
+        """
+        raise NotImplementedError()
+
+
+class NumpyParameterPool(IParameterPool):
+    def __init__(self):
+        self.__param_configs__ = dict()
+        self.__params__ = dict()
+
+    def append(self, conf):
+        if not isinstance(conf, ParameterConfig):
+            raise ValueError("conf must be ParameterConfig")
+
+        if not conf.IsInitialized():
+            raise ValueError("conf is not initialized")
+
+        self.__param_configs__[conf.name] = conf
+        self.__params__[conf.name] = None
+
+    def get_config(self, name):
+        if name not in self.__param_configs__:
+            raise ValueError("parameter %s is not appended" % name)
+
+        return self.__param_configs__[name]
+
+    def get_parameter(self, name, *args, **kwargs):
+        if name not in self.__params__:
+            raise ValueError("parameter %s is not appended" % name)
+
+        param = self.__params__[name]
+        if param is None:
+            shape = self.__param_configs__[name].dims
+            if len(shape) == 0:
+                raise ValueError("parameter %s is no shape" % name)
+            param = np.ndarray(
+                shape=[int(item) for item in shape], dtype='float32')
+            self.__params__[name] = param
+        return param
+
+    def get_names(self):
+        return self.__param_configs__.keys()
+
+
+def create(*topologies):
+    """
+    Create parameter pool by topologies.
+
+    :param topologies:
+    :return:
+    """
+    pool = NumpyParameterPool()
+    for topo in topologies:
+        if not isinstance(topo, ModelConfig):
+            raise ValueError(
+                'create must pass a topologies which type is ModelConfig')
+
+        for param in topo.parameters:
+            pool.append(param)
+    return pool
diff --git a/python/paddle/v2/trainer.py b/python/paddle/v2/trainer.py
new file mode 100644
index 0000000000000000000000000000000000000000..933700c615527773710bdde3c6e2beca8bb37139
--- /dev/null
+++ b/python/paddle/v2/trainer.py
@@ -0,0 +1,160 @@
+import collections
+from paddle.proto.ModelConfig_pb2 import ModelConfig
+import paddle.v2.parameters
+import paddle.v2.optimizer
+import py_paddle.swig_paddle as api
+from py_paddle import DataProviderConverter
+
+__all__ = ['ITrainer', 'SGDTrainer', 'CompleteTrainOneBatch', 'BaseEvent']
+
+
+class BaseEvent(object):
+    """
+    Just a marker class
+    """
+    pass
+
+
+class CompleteTrainOneBatch(BaseEvent):
+    def __init__(self, pass_id, batch_id, cost):
+        self.pass_id = pass_id
+        self.batch_id = batch_id
+        self.cost = cost
+
+
+def default_event_handler(event):
+    pass
+
+
+class ITrainer(object):
+    def train(self,
+              train_data_reader,
+              topology,
+              parameters,
+              test_data_reader=None,
+              event_handler=None):
+        raise NotImplementedError()
+
+
+class SGDTrainer(ITrainer):
+    def __init__(self, update_equation):
+        if not isinstance(update_equation, paddle.v2.optimizer.Optimizer):
+            raise ValueError()
+
+        self.__optimizer__ = update_equation
+
+    def train(self,
+              train_data_reader,
+              topology,
+              parameters,
+              num_passes=1,
+              test_data_reader=None,
+              event_handler=None,
+              batch_size=32,
+              data_types=None):
+        if event_handler is None:
+            event_handler = default_event_handler
+
+        __check_train_args__(**locals())
+
+        gm = api.GradientMachine.createFromConfigProto(
+            topology, api.CREATE_MODE_NORMAL, self.__optimizer__.enable_types())
+        assert isinstance(gm, api.GradientMachine)
+        __copy_parameter_from_pool__(gm, parameters)
+
+        updater = self.__optimizer__.create_local_updater()
+        assert isinstance(updater, api.ParameterUpdater)
+        updater.init(gm)
+
+        data_types_lists = []
+        for each in topology.input_layer_names:
+            if each not in data_types:
+                raise ValueError()
+            data_types_lists.append(data_types[each])
+
+        converter = DataProviderConverter(input_types=data_types_lists)
+
+        def input_reorder(func):
+            for item in func():
+                retv = []
+                for __layer_name__ in topology.input_layer_names:
+                    retv.append(item[__layer_name__])
+                yield retv
+
+        gm.start()
+
+        out_args = api.Arguments.createArguments(0)
+        for pass_id in xrange(num_passes):
+            updater.startPass()
+            for batch_id, data_batch in enumerate(
+                    __generator_to_batch__(
+                        input_reorder(train_data_reader),
+                        batch_size=batch_size)):
+                pass_type = updater.startBatch(len(data_batch))
+                gm.forwardBackward(converter(data_batch), out_args, pass_type)
+                for each_param in gm.getParameters():
+                    updater.update(each_param)
+                # Get cost. We use numpy to calculate total cost for this batch.
+                cost_vec = out_args.getSlotValue(0)
+                cost_vec = cost_vec.copyToNumpyMat()
+                cost = cost_vec.sum() / len(data_batch)
+                updater.finishBatch(cost)
+
+                event_handler(
+                    CompleteTrainOneBatch(
+                        pass_id=pass_id, batch_id=batch_id, cost=cost))
+
+            updater.finishPass()
+        gm.finish()
+
+
+def __generator_to_batch__(generator, batch_size):
+    ret_val = list()
+    for each_item in generator:
+        ret_val.append(each_item)
+        if len(ret_val) == batch_size:
+            yield ret_val
+            ret_val = list()
+    if len(ret_val) != 0:
+        yield ret_val
+
+
+def __copy_parameter_from_pool__(gm, pool):
+    """
+
+    :param gm:
+    :type gm: api.GradientMachine
+    :param pool:
+    :type pool: paddle.v2.parameters.IParameterPool
+    :return:
+    """
+    assert isinstance(pool, paddle.v2.parameters.IParameterPool)
+    for each_param in gm.getParameters():
+        name = each_param.getName()
+        param = pool.get_parameter(name,
+                                   paddle.v2.parameters.ParameterFlag.READ_ONLY)
+        each_param.getBuf(api.PARAMETER_VALUE).copyFromNumpyArray(param.flatten(
+        ).astype('float32'))
+
+
+def __check_train_args__(train_data_reader, topology, parameters,
+                         test_data_reader, event_handler, **kwargs):
+    if not callable(train_data_reader) or not isinstance(train_data_reader(),
+                                                         collections.Iterator):
+        raise ValueError('train_data_reader should be a function, '
+                         'which can return a iterator')
+
+    if test_data_reader is not None:
+        if not callable(test_data_reader) or not isinstance(
+                test_data_reader(), collections.Iterator):
+            raise ValueError('test_data_reader should be a function, which can '
+                             'return a iterator')
+
+    if not isinstance(topology, ModelConfig):
+        raise ValueError('topology should be a model config')
+
+    if not isinstance(parameters, paddle.v2.parameters.IParameterPool):
+        raise ValueError('parameters should be a parameter pool')
+
+    if not callable(event_handler):
+        raise ValueError('event handler should be a function')