diff --git a/src/model/Global.js b/src/model/Global.js
index da4da9995848082a648314db7af25e573e763ce5..96440b721f5ac62ac184cc38ce8da4ace79747e2 100644
--- a/src/model/Global.js
+++ b/src/model/Global.js
@@ -58,8 +58,6 @@ var GlobalModel = Model.extend({
          * @type {module:echarts/model/OptionManager}
          */
         this._optionManager = optionManager;
-
-        // this.settingTask = createTask();
     },
 
     setOption: function (option, optionPreprocessorFuncs) {
diff --git a/src/model/Series.js b/src/model/Series.js
index 4875cb19714c543c47892463a45361f08e56d3e1..d00a367ac221af7b7946621fcb03f37e63cdb703 100644
--- a/src/model/Series.js
+++ b/src/model/Series.js
@@ -69,12 +69,11 @@ var SeriesModel = ComponentModel.extend({
          */
         this.seriesIndex = this.componentIndex;
 
-        // this.settingTask = createTask();
-
         this.dataTask = createTask({
             count: dataTaskCount,
             reset: dataTaskReset
-        }, {model: this});
+        });
+        this.dataTask.context = {model: this};
 
         this.mergeDefaultAndTheme(option, ecModel);
 
diff --git a/src/stream/Scheduler.js b/src/stream/Scheduler.js
index f20dff4bc23e633e61e498a42fe281fac95a7924..33c5882e3ce4a01c961838eb9443040396e62401 100644
--- a/src/stream/Scheduler.js
+++ b/src/stream/Scheduler.js
@@ -249,22 +249,20 @@ function createSeriesStageTask(scheduler, stageHandler, stageHandlerRecord, ecMo
 
         // Init tasks for each seriesModel only once.
         // Reuse original task instance.
-        var task = seriesTaskMap.get(pipelineId);
-        if (!task) {
-            task = createTask({
+        var task = seriesTaskMap.get(pipelineId)
+            || seriesTaskMap.set(pipelineId, createTask({
                 reset: seriesTaskReset,
                 count: seriesTaskCount
-            }, {
-                model: seriesModel,
-                ecModel: ecModel,
-                api: api,
-                useClearVisual: stageHandler.isVisual && !stageHandler.isLayout,
-                plan: stageHandler.plan,
-                reset: stageHandler.reset,
-                scheduler: scheduler
-            });
-            seriesTaskMap.set(pipelineId, task);
-        }
+            }));
+        task.context = {
+            model: seriesModel,
+            ecModel: ecModel,
+            api: api,
+            useClearVisual: stageHandler.isVisual && !stageHandler.isLayout,
+            plan: stageHandler.plan,
+            reset: stageHandler.reset,
+            scheduler: scheduler
+        };
         pipe(scheduler, seriesModel, task);
     }
 
@@ -280,18 +278,15 @@ function createSeriesStageTask(scheduler, stageHandler, stageHandlerRecord, ecMo
 
 function createOverallStageTask(scheduler, stageHandler, stageHandlerRecord, ecModel, api) {
     var overallTask = stageHandlerRecord.overallTask = stageHandlerRecord.overallTask
-        || createTask(
-            // For overall task, the function only be called on reset stage.
-            {
-                reset: overallTaskReset
-            },
-            {
-                ecModel: ecModel,
-                api: api,
-                overallReset: stageHandler.overallReset,
-                scheduler: scheduler
-            }
-        );
+        // For overall task, the function only be called on reset stage.
+        || createTask({reset: overallTaskReset});
+
+    overallTask.context = {
+        ecModel: ecModel,
+        api: api,
+        overallReset: stageHandler.overallReset,
+        scheduler: scheduler
+    };
 
     // Reuse orignal stubs.
     var agentStubMap = overallTask.agentStubMap = overallTask.agentStubMap || createHashMap();
@@ -321,9 +316,9 @@ function createOverallStageTask(scheduler, stageHandler, stageHandlerRecord, ecM
     function createStub(seriesModel) {
         var pipelineId = seriesModel.uid;
         var stub = agentStubMap.get(pipelineId) || agentStubMap.set(pipelineId, createTask(
-            {plan: prepareData, reset: stubReset, onDirty: stubOnDirty},
-            {model: seriesModel, overallProgress: overallProgress}
+            {plan: prepareData, reset: stubReset, onDirty: stubOnDirty}
         ));
+        stub.context = {model: seriesModel, overallProgress: overallProgress};
         stub.agent = overallTask;
         stub.__block = overallProgress;
 
diff --git a/src/stream/task.js b/src/stream/task.js
index c8a1a229f2dca78da8b63e7b867362e45a8fc3a4..a5e02f2c779f5b2a1d19eba00270d524cde6f672 100644
--- a/src/stream/task.js
+++ b/src/stream/task.js
@@ -5,8 +5,8 @@ import { __DEV__ } from '../config';
  * @param {Object} define
  * @return See the return of `createTask`.
  */
-export function createTask(define, context) {
-    return new Task(define, context);
+export function createTask(define) {
+    return new Task(define);
 }
 
 /**
@@ -16,9 +16,8 @@ export function createTask(define, context) {
  * @param {Function} [define.plan] Returns 'reset' indicate reset immediately.
  * @param {Function} [define.count] count is used to determin data task.
  * @param {Function} [define.onDirty] count is used to determin data task.
- * @param {Object} [context]
  */
-function Task(define, context) {
+function Task(define) {
     define = define || {};
 
     this._reset = define.reset;
@@ -28,7 +27,9 @@ function Task(define, context) {
 
     this._dirty = true;
 
-    this.context = context || {};
+    // Context must be specified implicitly, to
+    // avoid miss update context when model changed.
+    this.context;
 }
 
 var taskProto = Task.prototype;
@@ -125,8 +126,7 @@ function reset(taskIns, skip) {
     taskIns._dueIndex = taskIns._outputDueEnd = taskIns._dueEnd = 0;
 
     taskIns._progress = !skip && taskIns._reset && taskIns._reset(
-        taskIns.context,
-        taskIns._upstream && taskIns._upstream.context
+        taskIns.context
     );
 
     var downstream = taskIns._downstream;
diff --git a/src/view/Chart.js b/src/view/Chart.js
index 45badbddbcd7f57d670bd89bec8f031a9708081f..2637b711a2ab8628de7d7557e2bea6818053305a 100644
--- a/src/view/Chart.js
+++ b/src/view/Chart.js
@@ -26,7 +26,8 @@ function Chart() {
     this.renderTask = createTask({
         plan: renderTaskPlan,
         reset: renderTaskReset
-    }, {view: this});
+    });
+    this.renderTask.context = {view: this};
 }
 
 Chart.prototype = {