Objective To discusses the reason of generating short hairs character and try to inbreed the sparse strain. Method To design the genetic experiment by means of sib mating and back cross mating. Result The sparse mouse appeared in F2 of the inbreeding and later generations of the back cross mating with the race mouse x F~ . It was proved that the sparse character is related with heredity. Conclusion The sparse character is autosomal recessive inheritance which is controlled by monogenic, and its heredity rule is completely consistent with Mendelian inheritance.