diff --git a/models/problem.js b/models/problem.js
index dbd74b2..5517fe9 100644
--- a/models/problem.js
+++ b/models/problem.js
@@ -349,12 +349,25 @@ class Problem extends Model {
     if (oldSize + size > syzoj.config.limit.testdata) throw new ErrorMessage('数据包太大。');
 
     await fs.moveAsync(filepath, path.join(dir, filename), { overwrite: true });
+    await fs.removeAsync(dir + '.zip');
+  }
+
+  async deleteTestdataSingleFile(filename) {
+    let dir = this.getTestdataPath();
+    let fs = Promise.promisifyAll(require('fs-extra')), path = require('path');
+    await fs.removeAsync(path.join(dir, filename));
+    await fs.removeAsync(dir + '.zip');
+  }
+
+  async makeTestdataZip() {
+    let dir = this.getTestdataPath();
+    if (!await syzoj.utils.isDir(dir)) throw new ErrorMessage('无测试数据。');
 
     let AdmZip = require('adm-zip');
     let zip = new AdmZip();
 
-    list = await this.listTestdata();
-    for (let file of list.files) zip.addLocalFile(path.join(dir, file.filename), '', file.filename);
+    let list = await this.listTestdata();
+    for (let file of list.files) zip.addLocalFile(require('path').join(dir, file.filename), '', file.filename);
     zip.writeZip(dir + '.zip');
   }
 
@@ -380,7 +393,7 @@ class Problem extends Model {
         return {
           filename: x,
           size: stat.size
-        }
+        };
       });
 
       list = list.filter(x => x);
@@ -395,13 +408,18 @@ class Problem extends Model {
         if (stat.isFile()) {
           res.zip = {
             size: stat.size
-          }
+          };
         }
-      } catch (e) {}
+      } catch (e) {
+        if (list) {
+          res.zip = {
+            size: null
+          };
+        }
+      }
 
       return res;
     } catch (e) {
-      console.log(e);
       return null;
     }
   }
diff --git a/modules/problem.js b/modules/problem.js
index 50bdf26..4e46988 100644
--- a/modules/problem.js
+++ b/modules/problem.js
@@ -676,6 +676,25 @@ app.post('/problem/:id/testdata/upload', app.multer.array('file'), async (req, r
   }
 });
 
+app.get('/problem/:id/testdata/delete/:filename', async (req, res) => {
+  try {
+    let id = parseInt(req.params.id);
+    let problem = await Problem.fromID(id);
+
+    if (!problem) throw new ErrorMessage('无此题目。');
+    if (!await problem.isAllowedEditBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
+
+    await problem.deleteTestdataSingleFile(req.params.filename);
+
+    res.redirect(syzoj.utils.makeUrl(['problem', id, 'testdata']));
+  } catch (e) {
+    syzoj.log(e);
+    res.render('error', {
+      err: e
+    });
+  }
+});
+
 app.get('/problem/:id/testdata/download/:filename?', async (req, res) => {
   try {
     let id = parseInt(req.params.id);
@@ -684,6 +703,12 @@ app.get('/problem/:id/testdata/download/:filename?', async (req, res) => {
     if (!problem) throw new ErrorMessage('无此题目。');
     if (!await problem.isAllowedUseBy(res.locals.user)) throw new ErrorMessage('您没有权限进行此操作。');
 
+    if (!req.params.filename) {
+      if (!await syzoj.utils.isFile(problem.getTestdataPath() + '.zip')) {
+        await problem.makeTestdataZip();
+      }
+    }
+
     let path = require('path');
     let filename = req.params.filename ? path.join(problem.getTestdataPath(), req.params.filename) : (problem.getTestdataPath() + '.zip');
     if (!await syzoj.utils.isFile(filename)) throw new ErrorMessage('文件不存在。');
diff --git a/views/problem_data.ejs b/views/problem_data.ejs
index 37c9245..c5f4c98 100644
--- a/views/problem_data.ejs
+++ b/views/problem_data.ejs
@@ -35,6 +35,11 @@ function getIcon(filename) {
 }
 %>
 <% include header %>
+<style>
+.ui.page.dimmer {
+  position: fixed;
+}
+</style>
 <div class="padding">
   <div class="ui grid">
     <div class="seven wide column">
@@ -49,22 +54,60 @@ function getIcon(filename) {
             <tr>
               <th class="left aligned">文件名</th>
               <th style="width: 100px">文件大小</th>
-              <th style="width: 50px">操作</th>
+              <th style="width: 35px">下载</th>
+              <% if (problem.allowedEdit) { %>
+                <th style="width: 35px">删除</th>
+              <% } %>
             </tr>
           </thead>
           <tbody>
             <% if (testdata.zip) { %>
             <tr>
               <td class="left aligned"><i class="file archive outline icon"></i> 完整数据包</td>
-              <td><%= syzoj.utils.formatSize(testdata.zip.size) %></td>
+              <td><%- !testdata.zip.size ? '<i class="minus icon"></i>' : syzoj.utils.formatSize(testdata.zip.size) %></td>
               <td><a style="color: #000; " href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'testdata', 'download']) %>"><i class="download icon"></i></td>
+              <% if (problem.allowedEdit) { %>
+                <td><i class="minus icon"></i></td>
+              <% } %>
             </tr>
             <% } %>
+            <% let i = 0; %>
             <% if (testdata.files) for (let file of testdata.files) { %>
+            <% i++; %>
             <tr>
               <td class="left aligned"><i class="<%= getIcon(file.filename) %> icon"></i> <%= file.filename %></td>
               <td><%= syzoj.utils.formatSize(file.size) %></td>
-              <td><a style="color: #000; " href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'testdata', 'download', file.filename]) %>"><i class="download icon"></i></td>
+              <td>
+                <a style="color: #000; " href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'testdata', 'download', file.filename]) %>">
+                  <i class="download icon"></i>
+                </a>
+              </td>
+              <% if (problem.allowedEdit) { %>
+                <td>
+                  <a style="color: #000; " onclick="$('#modal-delete-<%= i %>').modal('show')">
+                    <i class="remove icon"></i>
+                  </a>
+                  <div class="ui basic modal" id="modal-delete-<%= i %>">
+                    <div class="ui icon header">
+                      <i class="trash icon"></i>
+                      <p style="margin-top: 15px; ">删除文件</p>
+                    </div>
+                    <div class="content" style="text-align: center; ">
+                      <p>确认删除「 <samp><%= file.filename %></samp> 」吗？</p>
+                    </div>
+                    <div class="actions">
+                      <div class="ui red basic cancel inverted button">
+                        <i class="remove icon"></i>
+                        否
+                      </div>
+                      <a class="ui green ok inverted button" href="<%= syzoj.utils.makeUrl(['problem', problem.id, 'testdata', 'delete', file.filename]) %>">
+                        <i class="checkmark icon"></i>
+                        是
+                      </a>
+                    </div>
+                  </div>
+                </td>
+              <% } %>
             </tr>
             <% } %>
           </tbody>
@@ -73,18 +116,52 @@ function getIcon(filename) {
         <h4 style="text-align: center; ">无测试数据</h4>
       <% } %>
       <% if (problem.allowedEdit) { %>
-        <form class="ui form" action="<%= syzoj.utils.makeUrl(['problem', problem.id, 'testdata', 'upload']) %>" method="post" enctype="multipart/form-data">
+        <form id="form_upload" class="ui form" action="<%= syzoj.utils.makeUrl(['problem', problem.id, 'testdata', 'upload']) %>" method="post" enctype="multipart/form-data">
           <div class="inline fields">
             <div class="field" style="margin: 0 auto; ">
               <label for="answer">上传文件（可一次性上传多个）</label>
-              <input type="file" name="file" multiple>
+              <input type="file" name="file" multiple id="upload_file">
               <div class="ui center aligned vertical segment" style="padding-bottom: 0; ">
-                <button type="submit" class="ui button">提交</button>
+                <div class="ui button" onclick="check_replace()">提交</div>
                 <a href="<%= syzoj.utils.makeUrl(['problem', problem.id]) %>" class="ui blue button">返回题目</a>
               </div>
             </div>
           </div>
         </form>
+        <div class="ui basic modal" id="modal-replace">
+          <div class="ui icon header">
+            <i class="refresh icon"></i>
+            <p style="margin-top: 15px; ">替换文件</p>
+          </div>
+          <div class="content" style="text-align: center; ">
+            <p>确认替换以下文件吗？</p>
+            <div style="display: inline-block; text-align: left; " id="replaced_files"></div>
+          </div>
+          <div class="actions">
+            <div class="ui red basic cancel inverted button">
+              <i class="remove icon"></i>
+              否
+            </div>
+            <a class="ui green ok inverted button" onclick="$('#form_upload').submit()">
+              <i class="checkmark icon"></i>
+              是
+            </a>
+          </div>
+        </div>
+        <script>
+        function check_replace() {
+          var old_files = <%- JSON.stringify((testdata && testdata.files ? testdata.files : []).map(x => x.filename)) %>;
+          var replaced_files = Array.from($('#upload_file')[0].files).map(function (x) { return x.name; }).filter(function (x) { return old_files.includes(x); });
+          var s = '';
+          for (let file of replaced_files) s += '<samp>' + file + '</samp><br>';
+          if (s) {
+            $('#replaced_files').html(s);
+            $('#modal-replace').modal('show');
+          } else {
+            $('#form_upload').submit();
+          }
+        }
+        </script>
       <% } %>
     </div>
   </div>
diff --git a/views/problem_testcases.ejs b/views/problem_testcases.ejs
index f3b0b53..fddf6fd 100644
--- a/views/problem_testcases.ejs
+++ b/views/problem_testcases.ejs
@@ -30,8 +30,8 @@ let subtaskType = {
         <% } %>
           <% for (let testcase of subtask.cases) { %>
             <tr class="center aligned">
-              <td><%= testcase.input %></td>
-              <td><%= testcase.output %></td>
+              <td style="width: 50%; "><%= testcase.input %></td>
+              <td style="width: 50%; "><%= testcase.output %></td>
             </tr>
           <% } %>
       <% } %>