Objective To study the effect of Tribulus terrestris and the Epimedium complex on sexual function and sperm viability. Methods 50 male rats were randomly divided into five groups. The right testis of all rats except for the normal control group were removed, and a test substance or water was administered intragastrically for 40 d. On the 30th day, the mating test was performed. On the 35th day, the erectile time of the male rats was measured. On the 40th day, the male rats were sacrificed, the testicles, preputial glands, seminal vesicles and prostate glands were weighed, serum testosterone level was measured, sperm count, motility rate and viability were evaluated. Results Low and high doses of Tribulus terrestris and the Epimedium complex improved the capture rate ejaculation rate and ejaculation counts of hemi- castrated male rats (P<0.05). Compared with the normal control group, the low dose group had significantly higher serum testosterone level and seminal vesicle and prostate gland coefficients (P< 0.05), and the high dose group had a higher sperm motility rate and forward motile sperm count ( P< 0.05) and lower dead sperm count ( P< 0.01). Conclusions Tribulus terrestris and the Epimedium complex promote the secretion of testosterone and improve the sexual function of rats.