diff --git a/controllers/ProblemController.php b/controllers/ProblemController.php
index d484ca2e4..cd9d9347c 100644
--- a/controllers/ProblemController.php
+++ b/controllers/ProblemController.php
@@ -41,7 +41,7 @@ public function behaviors()
      * Lists all Problem models.
      * @return mixed
      */
-    public function actionIndex($showTags = 0, $page = 1, $tag = '')
+    public function actionIndex($showTags = 0, $page = 1, $per_page = 50, $tag = '', $q = '')
     {
 
         if (Yii::$app->setting->get('isContestMode') && (Yii::$app->user->isGuest || (!Yii::$app->user->identity->isAdmin()))) {
@@ -53,16 +53,20 @@ public function actionIndex($showTags = 0, $page = 1, $tag = '')
         if (Yii::$app->request->get('tag') != '') {
             $query->andWhere('tags LIKE :tag', [':tag' => '%' . Yii::$app->request->get('tag') . '%']);
         }
-        if (($post = Yii::$app->request->post())) {
-            $query->orWhere(['like', 'title', $post['q']])
-                ->orWhere(['like', 'id', $post['q']])
-                ->orWhere(['like', 'source', $post['q']]);
+        if (Yii::$app->request->get('q') != '') {
+            $query->orWhere(['like', 'title', $q])->orWhere(['like', 'id', $q])->orWhere(['like', 'source', $q]);
         }
+        // if (($post = Yii::$app->request->post())) {
+        //     $query->orWhere(['like', 'title', $post['q']])
+        //         ->orWhere(['like', 'id', $post['q']])
+        //         ->orWhere(['like', 'source', $post['q']]);
+        // }
         $query->andWhere('status<>' . Problem::STATUS_HIDDEN);
         $dataProvider = new ActiveDataProvider([
             'query' => $query,
             'pagination' => [
-                'pageSize' => 50
+                'pageSize' => $per_page,
+                'pageSizeParam' => 'per_page'
             ]
         ]);
 
@@ -95,7 +99,8 @@ public function actionIndex($showTags = 0, $page = 1, $tag = '')
             'solvedProblem' => $solvedProblem,
             'showTags' => $showTags,
             'page' => $page,
-            'tag' => $tag
+            'tag' => $tag,
+            'q' => $q
         ]);
     }
 
diff --git a/views/problem/index.php b/views/problem/index.php
index 6a9ca06e9..8821b4ba3 100644
--- a/views/problem/index.php
+++ b/views/problem/index.php
@@ -21,12 +21,12 @@
 
 
 
-<?= Html::beginForm('', 'post') ?>
+<?= Html::beginForm('/problem/index', 'get') ?>
 
 <div class="row">
     <div class="input-group">
         <div class="col-lg-6" style="margin-bottom: 1rem;">
-            <?= Html::textInput('q', '', ['class' => 'form-control', 'placeholder' => '题号 / 标题 / 来源']) ?>
+            <?= Html::textInput('q', $q, ['class' => 'form-control', 'placeholder' => '题号 / 标题 / 来源']) ?>
         </div>
 
         <div class="col-lg-6" style="margin-bottom: 1rem;">