Genetics is one of the main courses in agricultural and forestry colleges. However, there is large repetition of teaching contents and joining problems between genetics and the relative courses. The negative effects of above problems are discussed in this paper. In order to relieve the conflict between the increase of genetics contents and the decrease of teaching hours in genetics teaching of undergraduates and provide reference for future textbook compilation, some approaches on solving repetition of teaching content and suggestions on joining problems are put forward.