diff --git a/src/langs/common/enum.js b/src/langs/common/enum.js
index 08308bb..fa1e5e5 100644
--- a/src/langs/common/enum.js
+++ b/src/langs/common/enum.js
@@ -22,7 +22,8 @@ class SymbolEnum extends Enum {
       'REVERSE',
       'CONCAT',
       'JUDGE',
-      'RISK'
+      'RISK',
+      'YIELD'
     ], { name: 'symbol', ignoreCase: true });
   }
   assign() {
@@ -161,7 +162,8 @@ class TypeEnum extends Enum {
       'list',
       'object',
       'readable',
-      'writable'
+      'writable',
+      'iterator'
     ], { name: 'types', ignoreCase: true });
   }
 }
diff --git a/src/langs/common/items.js b/src/langs/common/items.js
index 9918d8f..e81c371 100644
--- a/src/langs/common/items.js
+++ b/src/langs/common/items.js
@@ -266,6 +266,14 @@ class GrammerReturn extends Grammer {
   }
 }
 
+class GrammerYield extends Grammer {
+  constructor(expr = '', type = '') {
+    super();
+    this.type = type; // null | grammer
+    this.expr = expr;
+  }
+}
+
 class GrammerLoop extends Grammer {
   constructor(type = '') {
     super();
@@ -539,6 +547,7 @@ module.exports = {
   GrammerCondition,
   GrammerException,
   GrammerReturnType,
+  GrammerYield,
 
   Behavior,
   BehaviorToMap,
diff --git a/src/langs/python/combinator.js b/src/langs/python/combinator.js
index 493eff8..3d09b35 100644
--- a/src/langs/python/combinator.js
+++ b/src/langs/python/combinator.js
@@ -1673,6 +1673,17 @@ class Combinator extends CombinatorBase {
     }
   }
 
+  grammerYield(emitter, gram) {
+    emitter.emit('yield ');
+    if (gram.type === 'grammer') {
+      this.grammer(emitter, gram.expr, false, false);
+    } else if (gram.type === 'string') {
+      emitter.emit('\'\'');
+    } else {
+      this.grammer(emitter, gram.expr, false, false);
+    }
+  }
+
   grammerContinue(emitter, gram) {
     emitter.emit('continue');
   }
diff --git a/src/langs/python/config.js b/src/langs/python/config.js
index 99f4450..ab15409 100644
--- a/src/langs/python/config.js
+++ b/src/langs/python/config.js
@@ -67,7 +67,8 @@ module.exports = {
     'WRITABLE': 'BinaryIO',
     'any': 'Any',
     'dict': 'Dict',
-    'list': 'List'
+    'list': 'List',
+    'iterator': 'Iterator'
   },
   typeMap: {
     'string': 'str',
@@ -94,7 +95,8 @@ module.exports = {
     'uint64': 'int',
     'any': 'any',
     'void': 'None',
-    'null': 'None'
+    'null': 'None',
+    'iterator': 'Iterator'
   },
   type: {
     // 'long': 'base',
@@ -110,7 +112,8 @@ module.exports = {
     'dict': 'complex',
     'list': 'complex',
     'READABLE': 'custom',
-    'WRITABLE': 'custom'
+    'WRITABLE': 'custom',
+    'iterator': 'complex'
   },
   exceptionMap: {
     'BASE': 'Exception',
diff --git a/src/langs/python2/combinator.js b/src/langs/python2/combinator.js
index 1429ce6..9f46cf4 100644
--- a/src/langs/python2/combinator.js
+++ b/src/langs/python2/combinator.js
@@ -1532,6 +1532,17 @@ class Combinator extends CombinatorBase {
     }
   }
 
+  grammerYield(emitter, gram) {
+    emitter.emit('yield ');
+    if (gram.type === 'grammer') {
+      this.grammer(emitter, gram.expr, false, false);
+    } else if (gram.type === 'string') {
+      emitter.emit('\'\'');
+    } else {
+      this.grammer(emitter, gram.expr, false, false);
+    }
+  }
+
   grammerContinue(emitter, gram) {
     emitter.emit('continue');
   }
diff --git a/src/resolver/client.js b/src/resolver/client.js
index b524f16..79c2b16 100644
--- a/src/resolver/client.js
+++ b/src/resolver/client.js
@@ -25,6 +25,7 @@ const {
   GrammerCondition,
   GrammerException,
   GrammerReturnType,
+  GrammerYield,
 
   BehaviorRetry,
   BehaviorToMap,
@@ -920,6 +921,31 @@ class ClientResolver extends BaseResolver {
         tryGram.setFinally(finallyGram);
       }
       node = tryGram;
+    } else if (stmt.type === 'yield') {
+      node = new GrammerYield();
+      if (typeof stmt.expr === 'undefined') {
+        node.type = 'null';
+      } else if (stmt.expr.type === 'null') {
+        node.type = 'null';
+      } else if (stmt.expr.type === 'call') {
+        let val = this.renderGrammerValue(null, stmt.expr);
+        node.expr = val;
+        node.type = 'grammer';
+      } else if (_isBasicType(stmt.expr.type)) {
+        node.type = stmt.expr.type;
+        node.expr = this.renderGrammerValue(null, stmt.expr);
+      } else {
+        node.expr = this.renderGrammerValue(null, stmt.expr);
+        node.type = 'grammer';
+      }
+      if (stmt.expectedType && stmt.expectedType.type === 'model') {
+        let expected = '';
+        if (stmt.expectedType.moduleName) {
+          expected += `${stmt.expectedType.moduleName}.`;
+        }
+        expected += stmt.expectedType.name;
+        node.expr = new BehaviorToModel(node.expr, expected);
+      }
     } else {
       debug.stack(stmt);
     }
diff --git a/tests/expected/python2/iterator/tea_python_tests/__init__.py b/tests/expected/python2/iterator/tea_python_tests/__init__.py
new file mode 100644
index 0000000..5becc17
--- /dev/null
+++ b/tests/expected/python2/iterator/tea_python_tests/__init__.py
@@ -0,0 +1 @@
+__version__ = "1.0.0"
diff --git a/tests/expected/python2/iterator/tea_python_tests/client.py b/tests/expected/python2/iterator/tea_python_tests/client.py
new file mode 100644
index 0000000..3630ce7
--- /dev/null
+++ b/tests/expected/python2/iterator/tea_python_tests/client.py
@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+# This file is auto-generated, don't edit it. Thanks.
+from __future__ import unicode_literals
+
+from Tea.converter import TeaConverter
+
+
+class Client(object):
+    def __init__(self):
+        pass
+
+    def test_1(self):
+        raise Exception('Un-implemented')
+
+    def test_2(self):
+        it = self.test_1()
+        for test in it:
+            yield test
+
+    def test_3(self, iter):
+        it = iter
+        str = ''
+        for i in it:
+            str = '%s, %s' % (TeaConverter.to_unicode(str), TeaConverter.to_unicode(i))
+        return str
+
+    def test_4(self, test):
+        pass
+
+    def test_5(self, iter):
+        # test3(iter);
+        self.test_4(iter)
diff --git a/tests/expected/python3/iterator/tea_python_tests/__init__.py b/tests/expected/python3/iterator/tea_python_tests/__init__.py
new file mode 100644
index 0000000..5becc17
--- /dev/null
+++ b/tests/expected/python3/iterator/tea_python_tests/__init__.py
@@ -0,0 +1 @@
+__version__ = "1.0.0"
diff --git a/tests/expected/python3/iterator/tea_python_tests/client.py b/tests/expected/python3/iterator/tea_python_tests/client.py
new file mode 100644
index 0000000..f81e5ec
--- /dev/null
+++ b/tests/expected/python3/iterator/tea_python_tests/client.py
@@ -0,0 +1,70 @@
+# -*- coding: utf-8 -*-
+# This file is auto-generated, don't edit it. Thanks.
+from typing import Any
+
+
+class Client:
+    def __init__(self):
+        pass
+
+    def test_1(self) -> Iterator:
+        raise Exception('Un-implemented')
+
+    async def test_1_async(self) -> Iterator:
+        raise Exception('Un-implemented')
+
+    def test_2(self) -> Iterator:
+        it = self.test_1()
+        for test in it:
+            yield test
+
+    async def test_2_async(self) -> Iterator:
+        it = await self.test_1_async()
+        for test in it:
+            yield test
+
+    def test_3(
+        self,
+        iter: Iterator,
+    ) -> str:
+        it = iter
+        str = ''
+        for i in it:
+            str = f'{str}, {i}'
+        return str
+
+    async def test_3_async(
+        self,
+        iter: Iterator,
+    ) -> str:
+        it = iter
+        str = ''
+        for i in it:
+            str = f'{str}, {i}'
+        return str
+
+    def test_4(
+        self,
+        test: Any,
+    ) -> None:
+        pass
+
+    async def test_4_async(
+        self,
+        test: Any,
+    ) -> None:
+        pass
+
+    def test_5(
+        self,
+        iter: Iterator,
+    ) -> None:
+        # test3(iter);
+        self.test_4(iter)
+
+    async def test_5_async(
+        self,
+        iter: Iterator,
+    ) -> None:
+        # test3(iter);
+        await self.test_4_async(iter)
diff --git a/tests/fixtures/iterator/Darafile b/tests/fixtures/iterator/Darafile
new file mode 100644
index 0000000..3329a3a
--- /dev/null
+++ b/tests/fixtures/iterator/Darafile
@@ -0,0 +1,6 @@
+{
+  "scope": "darabonba",
+  "name": "main",
+  "version": "0.0.1",
+  "main": "./main.dara"
+}
\ No newline at end of file
diff --git a/tests/fixtures/iterator/main.dara b/tests/fixtures/iterator/main.dara
new file mode 100644
index 0000000..9996111
--- /dev/null
+++ b/tests/fixtures/iterator/main.dara
@@ -0,0 +1,26 @@
+init(){}
+
+async function test1(): iterator[string];
+async function test2(): iterator[string]{
+  var it:iterator[string] = test1();
+  for(var test : it) {
+    yield test;
+  }
+}
+
+async function test3(iter: iterator[string]): string{
+  var it = iter;
+  var str : string = '';
+  for (var i : it) {
+    str = `${str}, ${i}`;
+  }
+  return str;
+}
+
+async function test4(test: any): void{
+}
+
+async function test5(iter: iterator[string]): void{
+  // test3(iter);
+  test4(iter);
+}
\ No newline at end of file
diff --git a/tests/python2.tests.js b/tests/python2.tests.js
index c4c4b4d..8fa3e3e 100644
--- a/tests/python2.tests.js
+++ b/tests/python2.tests.js
@@ -278,4 +278,23 @@ describe('Python Generator', function () {
 
     });
   });
+
+  it('iterator should ok', function () {
+    check('iterator', [
+      'tea_python_tests/client.py'
+    ],
+    {
+      python2: {
+        package: 'tea_python_tests',
+        clientName: 'client',
+        packageInfo: {
+          name: 'tea_python_tests',
+          desc: 'Generate setup.py',
+          github: 'https://github.com/',
+          author: 'Alibaba',
+          email: 'sdk-team@alibabacloud.com'
+        }
+      }
+    });
+  });
 });
\ No newline at end of file
diff --git a/tests/python3.tests.js b/tests/python3.tests.js
index 46b4ad7..cd1e5f9 100644
--- a/tests/python3.tests.js
+++ b/tests/python3.tests.js
@@ -290,4 +290,23 @@ describe('Python Generator', function () {
       }
     });
   });
+
+  it('iterator should ok', function () {
+    check('iterator', [
+      'tea_python_tests/client.py'
+    ],
+    {
+      python: {
+        package: 'tea_python_tests',
+        clientName: 'client',
+        packageInfo: {
+          name: 'tea_python_tests',
+          desc: 'Generate setup.py',
+          github: 'https://github.com/',
+          author: 'Alibaba',
+          email: 'sdk-team@alibabacloud.com'
+        }
+      }
+    });
+  });
 });
\ No newline at end of file