Many college students will go to tutors and tutors' institutions for social practice during their school days. Some students have achieved quite good results and won unanimous praise from students and parents, which proves that it is feasible for college students to teach mathematics in grade three, and they can also achieve excellent results. The reason is that college students themselves have learned the cultural knowledge of junior high school and passed the college entrance examination, which proves that college students' knowledge is enough to cope with junior high school mathematics. However, to be a good teacher, systematic knowledge is obviously not enough, just as many teachers are highly educated graduate students, but their teaching methods are rigid and scripted, which can not be recognized by most students, and the teaching effect is even worse than that of a college student. Therefore, when choosing college teachers, we can judge whether students have strong expressive ability, clear logical thinking and whether their personality conforms to the personality of the students being taught through communication with college students.