diff --git a/.gitignore b/.gitignore
index 78f2710..3674c4c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 node_modules/
 .idea/
+npm-debug.log
diff --git a/index.js b/index.js
index 8da4625..7924f8b 100644
--- a/index.js
+++ b/index.js
@@ -11,6 +11,7 @@ var util = require('util')
 var crypto = require('crypto')
 var minimatch = require('minimatch')
 var uploadedFiles = 0;
+var getEtag = require('./qetag');
 
 module.exports = function (qiniu, option) {
   option = option || {};
@@ -32,41 +33,42 @@ module.exports = function (qiniu, option) {
     if (isIgnore) return next();
 
     var fileKey = option.dir + ((!option.dir || option.dir[option.dir.length - 1]) === '/' ? '' : '/') + (option.versioning ? version + '/' : '') + filePath;
-    var fileHash = calcHash(file);
+    getEtag(file.path, function (fileHash) {
+      qs.push(Q.nbind(qn.stat, qn)(fileKey)
+        .spread(function (stat) {
+          // Skip when hash equal
+          if (stat.hash === fileHash) return false;
 
-    qs.push(Q.nbind(qn.stat, qn)(fileKey)
-      .spread(function (stat) {
-        // Skip when hash equal
-        if (stat.hash === fileHash) return false;
+          // Then delete
+          return Q.nbind(qn.delete, qn)(fileKey)
+        }, function () {
+          // Upload when not exists
+          return true;
+        })
+        .then(function (isUpload) {
+          if (isUpload === false) return false;
+          return Q.nbind(qn.upload, qn)(file._contents, {key: fileKey})
+        })
+        .then(function (stat) {
+          // No upload
+          if (stat === false) {
+            log('Skip:', colors.grey(filePath));
+            return;
+          }
 
-        // Then delete
-        return Q.nbind(qn.delete, qn)(fileKey)
-      }, function () {
-        // Upload when not exists
-        return true;
-      })
-      .then(function (isUpload) {
-        if (isUpload === false) return false;
-        return Q.nbind(qn.upload, qn)(file._contents, {key: fileKey})
-      })
-      .then(function (stat) {
-        // No upload
-        if (stat === false) {
-          log('Skip:', colors.grey(filePath));
-          return;
-        }
-
-        // Record hash
-        uploadedFiles++;
+          // Record hash
+          uploadedFiles++;
 
-        log('Upload:', colors.green(filePath), '→', colors.green(fileKey));
-      }, function (err) {
-        log('Error', colors.red(filePath), new PluginError('gulp-qiniu', err).message);
-        that.emit('Error', colors.red(filePath), new PluginError('gulp-qiniu', err));
-      })
-    )
+          log('Upload:', colors.green(filePath), '→', colors.green(fileKey));
+        }, function (err) {
+          log('Error', colors.red(filePath), new PluginError('gulp-qiniu', err).message);
+          that.emit('Error', colors.red(filePath), new PluginError('gulp-qiniu', err));
+        })
+      )
 
-    next();
+      next();   
+    });
+    
   }, function () {
     Q.all(qs)
       .then(function (rets) {
@@ -96,21 +98,4 @@ module.exports = function (qiniu, option) {
     }
     return target;
   }
-
-  /**
-   * Calc qiniu etag
-   *
-   * @param file
-   * @returns {*}
-   */
-  function calcHash(file) {
-    if (file.size > 1 << 22) return false;
-    var shasum = crypto.createHash('sha1');
-    shasum.update(file._contents);
-    var sha1 = shasum.digest();
-    var hash = new Buffer(1 + sha1.length);
-    hash[0] = 0x16;
-    sha1.copy(hash, 1);
-    return hash.toString('base64').replace('+', '-').replace('/', '_');
-  }
 };
diff --git a/qetag.js b/qetag.js
new file mode 100644
index 0000000..f7b04a2
--- /dev/null
+++ b/qetag.js
@@ -0,0 +1,79 @@
+// 计算文件的eTag，参数为buffer或者readableStream或者文件路径
+function getEtag(buffer,callback){
+
+  // 判断传入的参数是buffer还是stream还是filepath
+  var mode = 'buffer';
+
+  if(typeof buffer === 'string'){
+    buffer = require('fs').createReadStream(buffer);
+    mode='stream';
+  }else if(buffer instanceof require('stream')){
+    mode='stream';
+  }
+
+  // sha1算法
+  var sha1 = function(content){
+    var crypto = require('crypto');
+    var sha1 = crypto.createHash('sha1');
+    sha1.update(content);
+    return sha1.digest();
+  };
+
+  // 以4M为单位分割
+  var blockSize = 4*1024*1024;
+  var sha1String = [];
+  var prefix = 0x16;
+  var blockCount = 0;
+
+  switch(mode){
+    case 'buffer':
+      var bufferSize = buffer.length;
+      blockCount = Math.ceil(bufferSize / blockSize);
+
+      for(var i=0;i<blockCount;i++){
+        sha1String.push(sha1(buffer.slice(i*blockSize,(i+1)*blockSize)));
+      }
+      process.nextTick(function(){
+        callback(calcEtag());
+      });
+      break;
+    case 'stream':
+      var stream = buffer;
+      stream.on('readable', function() {
+        var chunk;
+        while (chunk = stream.read(blockSize)) {
+          sha1String.push(sha1(chunk));
+          blockCount++;
+        }
+      });
+      stream.on('end',function(){
+        callback(calcEtag());
+      });
+      break;
+  }
+
+  function calcEtag(){
+    if(!sha1String.length){
+      return 'Fto5o-5ea0sNMlW_75VgGJCv2AcJ';
+    }
+    var sha1Buffer = Buffer.concat(sha1String,blockCount * 20);
+
+    // 如果大于4M，则对各个块的sha1结果再次sha1
+    if(blockCount > 1){
+      prefix = 0x96;
+      sha1Buffer = sha1(sha1Buffer);
+    }
+
+    sha1Buffer = Buffer.concat(
+      [new Buffer([prefix]),sha1Buffer],
+      sha1Buffer.length + 1
+    );
+
+    return sha1Buffer.toString('base64')
+      .replace(/\//g,'_').replace(/\+/g,'-');
+
+  }
+
+}
+
+module.exports = getEtag;