diff --git a/paddle/fluid/recordio/CMakeLists.txt b/paddle/fluid/recordio/CMakeLists.txt
index 5d55709b4bbffafefcfef85993ead5f879a2a674..46188e0a5b0247bbe2ae05bd87ede94f4f075e24 100644
--- a/paddle/fluid/recordio/CMakeLists.txt
+++ b/paddle/fluid/recordio/CMakeLists.txt
@@ -1,5 +1,14 @@
-cc_library(header SRCS header.cc)
-cc_test(header_test SRCS header_test.cc DEPS header)
+# internal library.
 cc_library(io SRCS io.cc DEPS stringpiece)
 cc_test(io_test SRCS io_test.cc DEPS io)
+cc_library(header SRCS header.cc DEPS io)
+cc_test(header_test SRCS header_test.cc DEPS header)
 cc_library(chunk SRCS chunk.cc DEPS snappy)
+cc_test(chunk_test SRCS chunk_test.cc DEPS chunk)
+cc_library(range_scanner SRCS range_scanner.cc DEPS io chunk)
+cc_test(range_scanner_test SRCS range_scanner_test.cc DEPS range_scanner)
+cc_library(scanner SRCS scanner.cc DEPS range_scanner)
+cc_test(scanner_test SRCS scanner_test.cc DEPS scanner)
+# exported library.
+cc_library(recordio SRCS recordio.cc DEPS scanner chunk header)
+cc_test(recordio_test SRCS recordio_test.cc DEPS scanner)
diff --git a/paddle/fluid/recordio/chunk.h b/paddle/fluid/recordio/chunk.h
index a36c71cf4cce202aa57af74b7633f1555dbe6758..661364cd5d8019ca0b42bfb0d945903303271ac9 100644
--- a/paddle/fluid/recordio/chunk.h
+++ b/paddle/fluid/recordio/chunk.h
@@ -32,9 +32,10 @@ public:
   bool Dump(Stream* fo, Compressor ct);
   void Parse(Stream* fi, size_t offset);
   size_t NumBytes() { return num_bytes_; }
+  const std::string Record(int i) { return records_[i]; }
 
 private:
-  std::forward_list<std::string> records_;
+  std::forward_list<const std::string> records_;
   // sum of record lengths in bytes.
   size_t num_bytes_;
   DISABLE_COPY_AND_ASSIGN(Chunk);
diff --git a/paddle/fluid/recordio/header_test.cc b/paddle/fluid/recordio/header_test.cc
index 12e8f14ced426eeac43cb12253252cb3332d7534..d6ab26732901605417e1e9a18130cbe7bad87cba 100644
--- a/paddle/fluid/recordio/header_test.cc
+++ b/paddle/fluid/recordio/header_test.cc
@@ -22,12 +22,18 @@ using namespace paddle::recordio;
 
 TEST(Recordio, ChunkHead) {
   Header hdr(0, 1, Compressor::kGzip, 3);
-  Stream* oss = Stream::Open("/tmp/record_1", "w");
-  hdr->Write(oss);
+  {
+    Stream* oss = Stream::Open("/tmp/record_1", "w");
+    hdr.Write(oss);
+    delete oss;
+  }
 
-  // Stream* iss = Stream::Open("/tmp/record_1", "r");
-  // Header hdr2;
-  // hdr2.Parse(iss);
+  Header hdr2;
+  {
+    Stream* iss = Stream::Open("/tmp/record_1", "r");
+    hdr2.Parse(iss);
+    delete iss;
+  }
 
-  // EXPECT_TRUE(hdr == hdr2);
+  EXPECT_TRUE(hdr == hdr2);
 }
diff --git a/paddle/fluid/recordio/range_scanner.cc b/paddle/fluid/recordio/range_scanner.cc
index 4c0e80e2f88885725a036e56b84c6ce8487b6ab1..faf5078ba90ecbe561c3c2253d54b482c2fb783b 100644
--- a/paddle/fluid/recordio/range_scanner.cc
+++ b/paddle/fluid/recordio/range_scanner.cc
@@ -17,10 +17,37 @@
 namespace paddle {
 namespace recordio {
 
+void Index::LoadIndex(FileStream* fi) {
+  int64_t offset = 0;
+  while (!fi->Eof()) {
+    Header hdr;
+    hdr.Parse(fi);
+    chunk_offsets_.push_back(offset);
+    chunk_lens_.push_back(hdr.NumRecords());
+    chunk_records_.push_back(hdr.NumRecords());
+    num_records_ += hdr.NumRecords();
+    offset += hdr.CompressSize();
+  }
+}
+
 Index Index::ChunkIndex(int i) { Index idx; }
 
-RangeScanner::RangeScanner(std::istream is, Index idx, int start, int len)
-    : stream_(is.rdbuf()), index_(idx) {
+std::pair<int, int> Index::Locate(int record_idx) {
+  std::pair<int, int> range(-1, -1);
+  int sum = 0;
+  for (size_t i = 0; i < chunk_lens_.size(); ++i) {
+    int len = static_cast<int>(chunk_lens_[i]);
+    sum += len;
+    if (record_idx < sum) {
+      range.first = static_cast<int>(i);
+      range.second = record_idx - sum + len;
+    }
+  }
+  return range;
+}
+
+RangeScanner::RangeScanner(Stream* fi, Index idx, int start, int len)
+    : stream_(fi), index_(idx) {
   if (start < 0) {
     start = 0;
   }
@@ -30,16 +57,28 @@ RangeScanner::RangeScanner(std::istream is, Index idx, int start, int len)
 
   start_ = start;
   end_ = start + len;
-  cur_ = start - 1;
+  cur_ = start - 1;  // The intial status required by Scan
   chunk_index_ = -1;
-  // chunk_->reset(new Chunk());
+  chunk_.reset(new Chunk);
 }
 
-bool RangeScanner::Scan() {}
+bool RangeScanner::Scan() {
+  ++cur_;
+  if (cur_ >= end_) {
+    return false;
+  } else {
+    auto cursor = index_.Locate(cur_);
+    if (chunk_index_ != cursor.first) {
+      chunk_index_ = cursor.first;
+      chunk_->Parse(fi, index_.ChunkOffsets[chunk_index_]);
+    }
+  }
+  return true;
+}
 
 const std::string RangeScanner::Record() {
-  // int i = index_.Locate(cur_);
-  // return chunk_->Record(i);
+  auto cursor = index_.Locate(cur_);
+  return chunk_->Record(cursor.second);
 }
 
 }  // namespace recordio
diff --git a/paddle/fluid/recordio/range_scanner.h b/paddle/fluid/recordio/range_scanner.h
index 000a328d77478cb0780161f6842500fe653f526c..043fd8091e8e1ef9c3e1253c8073066070a9d355 100644
--- a/paddle/fluid/recordio/range_scanner.h
+++ b/paddle/fluid/recordio/range_scanner.h
@@ -14,6 +14,9 @@
 
 #pragma once
 
+#include <utility>
+
+#include "paddle/fluid/recordio/chunk.h"
 #include "paddle/fluid/recordio/io.h"
 
 namespace paddle {
@@ -26,29 +29,22 @@ namespace recordio {
 // for the correct encoding and decoding using Gob.
 class Index {
 public:
+  Index() : num_records_(0) {}
+  // LoadIndex scans the file and parse chunkOffsets, chunkLens, and len.
+  void LoadIndex(Stream* fi);
+  // NumRecords returns the total number of all records in a RecordIO file.
   int NumRecords() { return num_records_; }
   // NumChunks returns the total number of chunks in a RecordIO file.
   int NumChunks() { return chunk_lens_.size(); }
   // ChunkIndex return the Index of i-th Chunk.
   int ChunkIndex(int i);
 
+  int64_t ChunkOffsets(int i) { return chunk_offsets_[i]; }
+
   // Locate returns the index of chunk that contains the given record,
   // and the record index within the chunk.  It returns (-1, -1) if the
   // record is out of range.
-  void Locate(int record_idx, std::pair<int, int>* out) {
-    size_t sum = 0;
-    for (size_t i = 0; i < chunk_lens_.size(); ++i) {
-      sum += chunk_lens_[i];
-      if (static_cast<size_t>(record_idx) < sum) {
-        out->first = i;
-        out->second = record_idx - sum + chunk_lens_[i];
-        return;
-      }
-    }
-    // out->swap(std::make_pair<int,int>(-1, -1));
-    out->first = -1;
-    out->second = -1;
-  }
+  std::pair<int, int> Locate(int record_idx);
 
 private:
   // the offset of each chunk in a file.
@@ -62,12 +58,14 @@ private:
 };
 
 // RangeScanner
-// creates a scanner that sequencially reads records in the
-// range [start, start+len).  If start < 0, it scans from the
-// beginning.  If len < 0, it scans till the end of file.
 class RangeScanner {
 public:
+  // creates a scanner that sequencially reads records in the
+  // range [start, start+len).  If start < 0, it scans from the
+  // beginning.  If len < 0, it scans till the end of file.
   RangeScanner(Stream* fi, Index idx, int start, int end);
+  // Scan moves the cursor forward for one record and loads the chunk
+  // containing the record if not yet.
   bool Scan();
   const std::string Record();
 
diff --git a/paddle/fluid/recordio/range_scanner_test.cc b/paddle/fluid/recordio/range_scanner_test.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e365efc48b6aabb6d699ddb8099d28872efec2de
--- /dev/null
+++ b/paddle/fluid/recordio/range_scanner_test.cc
@@ -0,0 +1,23 @@
+//   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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.
+
+#include "paddle/fluid/recordio/range_scanner.h"
+
+#include "gtest/gtest.h"
+
+using namespace paddle::recordio;
+
+TEST(RangeScanner, Recordio) {
+  Stream* fo = Stream::Open("/tmp/record_range", "w");
+}
diff --git a/paddle/fluid/recordio/filesys.h b/paddle/fluid/recordio/recordio.cc
similarity index 79%
rename from paddle/fluid/recordio/filesys.h
rename to paddle/fluid/recordio/recordio.cc
index b21702bf3a0dcff282fb06edead46c3bf295602f..f8ed1fedf63998fe6c27ff9e94643aec7f8c7b6e 100644
--- a/paddle/fluid/recordio/filesys.h
+++ b/paddle/fluid/recordio/recordio.cc
@@ -12,13 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#pragma once
+#include "paddle/fluid/recordio/io.h"
+#include "paddle/fluid/string/piece.h"
 
-#include <fcntl.h>
-#include <stdio.h>
-#include <unistd.h>
-
-class DefaultFileSys {
-public:
-private:
-};
+namespace paddle {
+namespace recordio {}  // namespace recordio
+}  // namespace paddle
diff --git a/paddle/fluid/recordio/recordio.h b/paddle/fluid/recordio/recordio.h
new file mode 100644
index 0000000000000000000000000000000000000000..39ae953ce1a10c70067f4409f9bbf968743428da
--- /dev/null
+++ b/paddle/fluid/recordio/recordio.h
@@ -0,0 +1,20 @@
+//   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// 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.
+#pragma once
+
+#include "paddle/fluid/recordio/chunk.h"
+#include "paddle/fluid/recordio/header.h"
+#include "paddle/fluid/recordio/io.h"
+#include "paddle/fluid/recordio/scanner.h"
+#include "paddle/fluid/recordio/writer.h"
diff --git a/paddle/fluid/recordio/scanner.cc b/paddle/fluid/recordio/scanner.cc
index d5464ae9d8df8554ec1f567b7332263ed0d2fd7c..45cf472e9d070a795e0c43fba73ca0235b205efc 100644
--- a/paddle/fluid/recordio/scanner.cc
+++ b/paddle/fluid/recordio/scanner.cc
@@ -31,7 +31,7 @@ Scanner::Scanner(const char* paths)
 }
 
 bool Scanner::Scan() {
-  if (err_ == -1 || end_ == true) {
+  if (end_ == true) {
     return false;
   }
   if (cur_scanner_ == nullptr) {
@@ -39,20 +39,30 @@ bool Scanner::Scan() {
       end_ = true;
       return false;
     }
-    if (err_ == -1) {
-      return false;
-    }
   }
   if (!cur_scanner_->Scan()) {
-    if (err_ == -1) {
-      return false;
-    }
+    end_ = true;
+    cur_file_ = nullptr;
+    return false;
   }
-
   return true;
 }
 
-bool Scanner::NextFile() {}
+bool Scanner::NextFile() {
+  if (path_idx_ >= paths_.size()) {
+    return false;
+  }
+  std::string path = paths_[path_idx_];
+  ++path_idx_;
+  cur_file_ = Stream::Open(path);
+  if (cur_file_ == nullptr) {
+    return false;
+  }
+  Index idx;
+  idx.LoadIndex(cur_file_);
+  cur_scanner_ = RangeScanner(cur_file_, idx, 0, -1);
+  return true;
+}
 
 }  // namespace recordio
 }  // namespace paddle