diff --git a/problem/migrations/0004_auto_20170501_0637.py b/problem/migrations/0004_auto_20170501_0637.py
new file mode 100644
index 0000000..5d55ace
--- /dev/null
+++ b/problem/migrations/0004_auto_20170501_0637.py
@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.6 on 2017-05-01 06:37
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('problem', '0003_auto_20170217_0820'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='contestproblem',
+            name='total_accepted_number',
+            field=models.BigIntegerField(default=0),
+        ),
+        migrations.AlterField(
+            model_name='contestproblem',
+            name='total_submit_number',
+            field=models.BigIntegerField(default=0),
+        ),
+        migrations.AlterField(
+            model_name='problem',
+            name='total_accepted_number',
+            field=models.BigIntegerField(default=0),
+        ),
+        migrations.AlterField(
+            model_name='problem',
+            name='total_submit_number',
+            field=models.BigIntegerField(default=0),
+        ),
+    ]
diff --git a/problem/models.py b/problem/models.py
index 17d4e5d..61cc8f4 100644
--- a/problem/models.py
+++ b/problem/models.py
@@ -18,6 +18,12 @@ class ProblemRuleType(object):
     OI = "OI"
 
 
+class ProblemDifficulty(object):
+    High = "High"
+    Mid = "Mid"
+    Low = "Low"
+
+
 class AbstractProblem(models.Model):
     title = models.CharField(max_length=128)
     # HTML
@@ -49,19 +55,19 @@ class AbstractProblem(models.Model):
     difficulty = models.CharField(max_length=32)
     tags = models.ManyToManyField(ProblemTag)
     source = models.CharField(max_length=200, blank=True, null=True)
-    total_submit_number = models.IntegerField(default=0)
-    total_accepted_number = models.IntegerField(default=0)
+    total_submit_number = models.BigIntegerField(default=0)
+    total_accepted_number = models.BigIntegerField(default=0)
 
     class Meta:
         db_table = "problem"
         abstract = True
 
     def add_submission_number(self):
-        self.accepted_problem_number = models.F("total_submit_number") + 1
+        self.total_submit_number = models.F("total_submit_number") + 1
         self.save()
 
     def add_ac_number(self):
-        self.accepted_problem_number = models.F("total_accepted_number") + 1
+        self.total_accepted_number = models.F("total_accepted_number") + 1
         self.save()
 
 
@@ -77,4 +83,4 @@ class ContestProblem(AbstractProblem):
 
     class Meta:
         db_table = "contest_problem"
-        unique_together = (("_id", "contest"), )
+        unique_together = (("_id", "contest"),)
diff --git a/problem/tests.py b/problem/tests.py
index d80262a..caa6ad6 100644
--- a/problem/tests.py
+++ b/problem/tests.py
@@ -17,7 +17,9 @@ class ProblemTagListAPITest(APITestCase):
         ProblemTag.objects.create(name="name2")
         resp = self.client.get(self.reverse("problem_tag_list_api"))
         self.assertSuccess(resp)
-        self.assertEqual(resp.data["data"], ["name1", "name2"])
+        resp_data = resp.data["data"]
+        self.assertEqual(resp_data[0]["name"], "name1")
+        self.assertEqual(resp_data[1]["name"], "name2")
 
 
 class TestCaseUploadAPITest(APITestCase):
@@ -27,7 +29,8 @@ class TestCaseUploadAPITest(APITestCase):
         self.create_super_admin()
 
     def test_filter_file_name(self):
-        self.assertEqual(self.api.filter_name_list(["1.in", "1.out", "2.in", ".DS_Store"], spj=False), ["1.in", "1.out"])
+        self.assertEqual(self.api.filter_name_list(["1.in", "1.out", "2.in", ".DS_Store"], spj=False),
+                         ["1.in", "1.out"])
         self.assertEqual(self.api.filter_name_list(["2.in", "2.out"], spj=False), [])
 
         self.assertEqual(self.api.filter_name_list(["1.in", "1.out", "2.in"], spj=True), ["1.in", "2.in"])
@@ -76,9 +79,9 @@ class TestCaseUploadAPITest(APITestCase):
                     self.assertEqual(f.read(), name + "\n" + name + "\n" + "end")
 
 
-class ProblemAPITest(APITestCase):
+class ProblemAdminAPITest(APITestCase):
     def setUp(self):
-        self.url = self.reverse("problem_api")
+        self.url = self.reverse("problem_admin_api")
         self.create_super_admin()
         self.data = {"_id": "A-110", "title": "test", "description": "<p>test</p>", "input_description": "test",
                      "output_description": "test", "time_limit": 1000, "memory_limit": 256, "difficulty": "Low",
diff --git a/problem/urls/admin.py b/problem/urls/admin.py
index b4813c5..d123f35 100644
--- a/problem/urls/admin.py
+++ b/problem/urls/admin.py
@@ -4,6 +4,6 @@ from ..views.admin import ContestProblemAPI, ProblemAPI, TestCaseUploadAPI
 
 urlpatterns = [
     url(r"^test_case/upload/?$", TestCaseUploadAPI.as_view(), name="test_case_upload_api"),
-    url(r"^problem/?$", ProblemAPI.as_view(), name="problem_api"),
+    url(r"^problem/?$", ProblemAPI.as_view(), name="problem_admin_api"),
     url(r"^contest/problem/?$", ContestProblemAPI.as_view(), name="contest_problem_api")
 ]
diff --git a/problem/urls/oj.py b/problem/urls/oj.py
index a7613f1..5e7e6be 100644
--- a/problem/urls/oj.py
+++ b/problem/urls/oj.py
@@ -1,7 +1,8 @@
 from django.conf.urls import url
 
-from ..views.oj import ProblemTagAPI
+from ..views.oj import ProblemTagAPI, ProblemAPI
 
 urlpatterns = [
-    url(r"^problem/tags/?$", ProblemTagAPI.as_view(), name="problem_tag_list_api")
+    url(r"^problem/tags/?$", ProblemTagAPI.as_view(), name="problem_tag_list_api"),
+    url(r"^problems/?$", ProblemAPI.as_view(), name="problem_list_api"),
 ]
diff --git a/problem/views/oj.py b/problem/views/oj.py
index 94496ce..611c2c9 100644
--- a/problem/views/oj.py
+++ b/problem/views/oj.py
@@ -1,8 +1,44 @@
+from django.db.models import Q
 from utils.api import APIView
 
-from ..models import ProblemTag
+from ..models import ProblemTag, Problem
+from ..serializers import ProblemSerializer, TagSerializer
 
 
 class ProblemTagAPI(APIView):
     def get(self, request):
-        return self.success([item.name for item in ProblemTag.objects.all().order_by("id")])
+        return self.success(TagSerializer(ProblemTag.objects.all(), many=True).data)
+
+
+class ProblemAPI(APIView):
+    def get(self, request):
+        # 问题详情页
+        problem_id = request.GET.get("id")
+        if problem_id:
+            try:
+                problem = Problem.objects.get(id=problem_id)
+                return self.success(ProblemSerializer(problem).data)
+            except Problem.DoesNotExist:
+                return self.error("Problem does not exist")
+
+        problems = Problem.objects.filter(visible=True)
+        # 按照标签筛选
+        tag_text = request.GET.get("tag", None)
+        if tag_text:
+            try:
+                tag = ProblemTag.objects.get(name=tag_text)
+            except ProblemTag.DoesNotExist:
+                return self.error("The Tag does not exist.")
+            problems = tag.problem_set.all().filter(visible=True)
+
+        # 搜索的情况
+        keyword = request.GET.get("keyword", "").strip()
+        if keyword:
+            problems = problems.filter(Q(title__contains=keyword) | Q(description__contains=keyword))
+
+        # 难度筛选
+        difficulty_rank = request.GET.get("difficulty", None)
+        if difficulty_rank:
+            problems = problems.filter(difficulty=difficulty_rank)
+
+        return self.success(self.paginate_data(request, problems, ProblemSerializer))