Students of Yi nationality of "the First Class" have poor Chinese language skills, weak basic knowledge and weak self-study consciousness, which makes it difficult for mathematics teaching in "the First Class". Then how to improve the quality of the teaching of mathematics in "the first class" is a question needed to be pondering. In this paper, the teaching of mathematics in "the First Class" of School of Yi Language and Culture of Xichang University is taken as an example. By introducing the teaching model of "students teach students", the students' enthusiasm is fully mobilized and it attracts more students to participate in teaching activities so as to solve the problem in the mathematics teaching of "the First Class". It also provides a new method for college mathematics teaching of "the First Class". In the specific implementation processes, the transformation of teaching model will be achieved and the teaching efficiency and effectiveness will be improved