Objective: To analyze clinical effects of different ovarian stimulation protocols among women with polycystic ovary syndrome undergoing intrauterine insemination (IUI). Methods: A retrospective study was conducted to analyze 634 IUI cycles for patients with PCOS from January 2010 to December 2013. According to different ovarian stimulation protocols, patients were divided into 8 groups (CC, LE, HMG, FSH, CC+HMG, CC+FSH, LE+HMG, LE+FSH). The essential characteristics, follicular development situation, endometrial thickness, duration and dose of gonadotropin (Gn) used, pregnancy outcomes and complications were evaluated among 8 groups. Results: The total number of dominant follicles and the total number of ruptured follicles in Gn groups（FSH, HMG）and groups combined with CC (CC+HMG, CC+FSH) were significantly greater than those of simple oral drugs (CC, LE) and groups combined with LE（LE+HMG, LE+FSH, P<0.05). The rate of mono mature follicle in LE group was the highest (82.89%, P<0.01). The days to human chorionic gonadotropin (hCG) injection in HMG group, CC + HMG group, LE + HMG group were significantly greater than those of simple oral drug groups (P<0.05). Significant differences were found in the average thickness of endometrium and the number of endometrial thickness less than 8mm at IUI day between CC group and the remaining groups (P<0.05). The duration and dose of Gn used in combination groups (CC+HMG, CC+FSH, LE+HMG and LE+FSH) were significantly less than those of Gn groups (P<0.05). Clinical pregnancy rate of CC group was the lowest (P<0.05), and clinical pregnancy rates of the remaining groups had no significant differences (P>0.05). A total of 4 cases of mild ovarian hyper-stimulation syndrome (OHSS) occurred in Gn groups and 14 cases of multiple pregnancy were found in Gn groups (n=11) and combination groups (n=3). Conclusion: The clinical pregnancy rate of CC is the lowest that may be associated with the anti-estrogen effects which plays a role in endometrial thickness. The rate of mono mature follicle of LE group is the highest and women in LE group achieve a satisfactory clinical pregnancy rate. The clinical pregnancy rates of combination group are equal to those of Gn groups, but combination groups is worth promoting due to the the less duration and dose of Gn used as well as lower rates of OHSS and multiple pregnancy.