〔Abstract〕 Objective To investigate the effect of lansterol synthase(LSS) gene knockout on reproductive function in male mice. Methods 30 male and female 8-week-old LSS+/+(WT) and LSS+/-(KO) mice were selected,and respectively according to ♂WT × ♀WT, ♂WT × ♀KO, ♂KO × ♀WT, ♂KO × ♀KO carries out 1 ∶ 1 cages for four months, and the number of litters per litter and reproductive cycle were counted. The serum of LSS+/+（WT） and LSS+/-（KO） mice was taken for sex hormone testing. The apoptosis of spermatogenic cells in the testis was observed by TUNEL staining. Western blot was used to detect the expression of Tubulin, LSS and apoptosis-related protein(GPX4/Bax/Bcl-2) in testis tissue.Results The breeding results showed that there was a statistically difference in the number of litters per litter between ♂WT × ♀WT and ♂KO × ♀KO, and there was no difference in the other groups. There was no statistically difference in the four groups in the reproductive cycle. There was no statistically difference between the sex hormone test results of WT and KO mice. TUNEL staining results showed that there was an increase in spermatogenic cell apoptosis in the testis tissue of the knockout mice. In the results of Western blot, there was no difference in the expression of apoptosis-related proteins(GPX4/Bax/Bcl-2)in KO mice compared with WT mice.Conclusion Loss of LSS gene function can lead to increased apoptosis of mouse spermatogenic cells, which may affect the fertility of mice.