diff --git a/apps/api/src/routes/submission.ts b/apps/api/src/routes/submission.ts
index c03fe6c..d416e8d 100644
--- a/apps/api/src/routes/submission.ts
+++ b/apps/api/src/routes/submission.ts
@@ -208,6 +208,36 @@ submissionRoutes.get("/submissions/today-count", async (c) => {
   return success(c, row?.value ?? 0)
 })
 
+/**
+ * 近半年交过代码或流程图的班级，给提交列表的班级下拉补上网站配置里没有的那些。
+ * 配置的班级列表管的是「注册时能选哪些班」，毕业、换届的班从里面摘掉之后
+ * 还在交（生产上 247 摘了之后四个月里交了三百多条），下拉里却选不到它。
+ * 只收 3~4 位数字的班级号，`user.class_name` 里有几个手填的名字不算班。
+ */
+submissionRoutes.get("/submissions/classes", requireTeacher, async (c) => {
+  const since = new Date(Date.now() - 180 * 24 * 3600 * 1000).toISOString()
+  const active = db
+    .selectDistinct({ userId: schema.submission.userId })
+    .from(schema.submission)
+    .where(
+      and(isNull(schema.submission.contestId), sql`${schema.submission.createTime} >= ${since}`),
+    )
+    .union(
+      db
+        .selectDistinct({ userId: schema.flowchartSubmission.userId })
+        .from(schema.flowchartSubmission)
+        .where(sql`${schema.flowchartSubmission.createTime} >= ${since}`),
+    )
+    .as("active")
+  const rows = await db
+    .selectDistinct({ className: schema.user.className })
+    .from(active)
+    .innerJoin(schema.user, eq(schema.user.id, active.userId))
+    .where(sql`${schema.user.className} ~ '^[0-9]{3,4}$'`)
+    .orderBy(schema.user.className)
+  return success(c, rows.map((row) => row.className!) satisfies string[])
+})
+
 submissionRoutes.route("/", submissionStatisticsRoutes)
 
 // 老师也能重判：旧栈只给超管，前端却一直给老师亮着按钮，老师点了只会「权限不足」。
diff --git a/apps/web/src/oj/api.ts b/apps/web/src/oj/api.ts
index 1e4b806..f12802d 100644
--- a/apps/web/src/oj/api.ts
+++ b/apps/web/src/oj/api.ts
@@ -167,6 +167,11 @@ export function getTodaySubmissionCount(language?: string) {
   return api.get<number>("submissions/today-count", { params: { language } })
 }
 
+/** 近半年有提交的班级（老师用），补上网站配置里已经摘掉的班 */
+export function getSubmissionClasses() {
+  return api.get<string[]>("submissions/classes")
+}
+
 /** 「今日提交数」标签点开的统计。公开接口，口径同那颗标签：今天 + 非比赛提交 */
 export function getTodaySubmissionStatistics() {
   return api.get<TodaySubmissionStatistics>("submissions/today-statistics")
diff --git a/apps/web/src/oj/submission/list.vue b/apps/web/src/oj/submission/list.vue
index 069bd5d..8d18536 100644
--- a/apps/web/src/oj/submission/list.vue
+++ b/apps/web/src/oj/submission/list.vue
@@ -7,6 +7,7 @@ import {
   adminRejudge,
   getClassLesson,
   getFlowchartSubmissions,
+  getSubmissionClasses,
   getSubmissions,
   getTodaySubmissionCount,
   retryFlowchartSubmission,
@@ -444,11 +445,33 @@ const languageOptions = [
   { label: "SQL", value: "SQL" },
 ]
 
+// 配置里的班级列表是「注册时能选的班」，摘掉的老班还在交，得从提交里补出来
+const activeClasses = ref<string[]>([])
+watch(
+  teacher,
+  async (isTeacher) => {
+    if (!isTeacher || activeClasses.value.length) return
+    try {
+      activeClasses.value = await getSubmissionClasses()
+    } catch {
+      // 补不上就只有配置里那些，不打扰
+    }
+  },
+  { immediate: true },
+)
+
 const classOptions = computed(() => {
   const list = configStore.config?.classList ?? []
-  // 带进来的班级不在配置里（老班、手打的）也要显示得出来，不然框里是空的却在筛
-  const all = query.className && !list.includes(query.className) ? [query.className, ...list] : list
-  return all.map((item) => ({ label: classLabel(item), value: item }))
+  const others = activeClasses.value.filter((item) => !list.includes(item)).reverse()
+  // 带进来的班级哪边都没有（手打的）也要显示得出来，不然框里是空的却在筛
+  if (query.className && !list.includes(query.className) && !others.includes(query.className))
+    others.unshift(query.className)
+  const option = (item: string) => ({ label: classLabel(item), value: item })
+  if (!others.length) return list.map(option)
+  return [
+    { type: "group", label: "班级列表", key: "listed", children: list.map(option) },
+    { type: "group", label: "不在班级列表里", key: "others", children: others.map(option) },
+  ]
 })
 
 const contestProblemOptions = computed(() => [