diff --git a/src/Jiaowu.Api/Infrastructure/Persistence/DemoDataSeeder.cs b/src/Jiaowu.Api/Infrastructure/Persistence/DemoDataSeeder.cs
index 639f605..48d2c3e 100644
--- a/src/Jiaowu.Api/Infrastructure/Persistence/DemoDataSeeder.cs
+++ b/src/Jiaowu.Api/Infrastructure/Persistence/DemoDataSeeder.cs
@@ -457,16 +457,18 @@ public sealed class DemoDataSeeder(
             .Select(x => (x.TeacherId, x.CourseId))
             .ToHashSet();
         var additions = new List<TeacherCourseApplication>();
-        for (var teacherIndex = 0; teacherIndex < teachers.Count; teacherIndex++)
+        foreach (var teacher in teachers)
         {
-            var teacher = teachers[teacherIndex];
             var professionalCourses = courses
                 .Where(x => x.CollegeId == teacher.CollegeId &&
-                            x.Nature is CourseNature.MajorRequired or
-                                CourseNature.MajorElective or CourseNature.Practice)
+                            x.Nature is (CourseNature.MajorRequired or
+                                CourseNature.MajorElective or CourseNature.Practice))
                 .Take(4);
-            var selectedPublicCourses = Enumerable.Range(0, 2)
-                .Select(offset => publicCourses[(teacherIndex + offset) % publicCourses.Count]);
+            var collegePublicCourses = publicCourses
+                .Where(x => x.CollegeId == teacher.CollegeId)
+                .ToList();
+            var selectedPublicCourses = collegePublicCourses
+                .Take(2);
             foreach (var course in professionalCourses
                          .Concat(selectedPublicCourses)
                          .DistinctBy(x => x.Id))
diff --git a/tests/Jiaowu.Api.Tests/DemoDataSeederTests.cs b/tests/Jiaowu.Api.Tests/DemoDataSeederTests.cs
index 61ade12..98c641a 100644
--- a/tests/Jiaowu.Api.Tests/DemoDataSeederTests.cs
+++ b/tests/Jiaowu.Api.Tests/DemoDataSeederTests.cs
@@ -31,7 +31,15 @@ public sealed class DemoDataSeederTests
         Assert.Equal(128, await db.Teachers.CountAsync());
         Assert.Equal(3640, await db.Students.CountAsync());
         Assert.Equal(148, await db.Courses.CountAsync());
-        Assert.Equal(736, await db.TeacherCourseApplications.CountAsync());
+        Assert.Equal(624, await db.TeacherCourseApplications.CountAsync());
+        var crossCollegeApplications = await (
+            from application in db.TeacherCourseApplications
+            join teacher in db.Teachers on application.TeacherId equals teacher.Id
+            join course in db.Courses on application.CourseId equals course.Id
+            where teacher.CollegeId != course.CollegeId
+            select application.Id)
+            .CountAsync();
+        Assert.Equal(0, crossCollegeApplications);
         Assert.Equal(1, await db.AcademicTerms.CountAsync(x => x.IsCurrent));
         Assert.Equal(30, await db.Classrooms.CountAsync());
     }