Abstract：Objective：To observe the effect of the therapy of Ziyin Buyang prescription on levels of sex hormones，ovulation and pregnancy in patients with polycystic ovary syndrome(PCOS). Methods：A total of 200 PCOS female patients with infertility caused by ovulation dysfunction were randomly divided into the control group and the observation group，with 100 cases in each group. The control group，with 489 cycles and 383 ovulation cycles， was treated with the routine western medicine； the observation group， with 492 cycles and 403 ovulation cycles，was additionally treated with Ziyin Buyang prescription based on the treatment of the control group. The clinical effects in the two groups were observed. Before and after treatment， the levels of serum follicle stimulating hormone(FSH)， luteinizing hormone(LH)， and testosterone(T) were compared between the two groups. The dosage and time of the using of human chorionic gonadotropin(HCG) in ovulation induction cycle were recorded. The development of follicle， normal ovulation cycles， small follicle cycles， cycles with luteinized unruptured follicle syndrome(LUFS)， cycles being cancelled due to no responses，tendency of ovarian hyperstimulation syndrome(OHSS)，cycle pregnancy rates，and pregnancy rates were counted. Results：The total effective rate was 78.00% in the observation group，higher than that of 62.00% in the control group(P＜0.05). After treatment，the levels of serum FSH in the two groups were increased when compared with those before treatment(P＜0.05)，and the levels of LH and T were decreased(P＜0.05)； after treatment， the level of serum FSH in the observation group was higher than that in the control group(P＜0.05)，and the levels of LH and T were lower (P＜0.05). After treatment，the dosage of HCG in the observation group was less than that in the control group(P＜0.05)，and the time of HCG using was shorter(P＜0.05). The number of patients with cycles of no follicular development in the observation group was smaller than that in the control group(P＜0.05)，and the number of patients with cycles of single or multi-follicular development was larger(P＜0.05). There was no significant difference being found in the comparison of small follicle cycle between the two groups(P＞ 0.05)； there were more normal ovulation cycles in the observation group than in the control group(P＜ 0.05)，and there were less LUFS cycles in the observation group than in the control group(P＜0.05). There were less cycles being cancelled due to no responses and less cycles with OHSS tendency in the observation group than in the control group(P＜0.05)，and the cycle pregnancy rate and pregnancy rate in the observation group were higher(P＜0.05). No serious adverse reactions occurred in both groups during treatment，and mild adverse reactions disappeared after stopping treatment. Conclusion：The therapy of Ziyin Buyang prescription based on routine western medicine has a good effect of assisting pregnancy， which can shorten the time of using and dosage of HCG，improve the levels of sex hormones and follicular development，and increase the normal ovulation cycles and pregnancy rates of patients.