Abstract: Objective To analyze the effect of endometrial pretreatment on ovulation function and pregnancy outcome in infertile women with polycystic ovary syndrome(PCOS). Methods A total of 100 patients with PCOS enrolled in the Second People's Hospital of Linhai from March 2015 to December 2017 were divided into control group and observation group according to the method of random number table, with 50 cases in each group. The control group was given clomiphene, and the observation group was pretreated with Diane 35 and metformin before clomiphene. Before and after treatment, the levels of sex hormone(serum LH, FSH, T, E2) and fasting insulin level(FINS) were compared between the two groups. Results After treatment, the difference of endometrial blood flow perfusion type(Hc=10.100, P=0.006) and thickness(t=7.203, P<0.001) between the two groups was statistically significant. The improvement of LH(t=5.012, P<0.001), FSH(t=2.088, P=0.037), T(t=2.360, P=0.018), E2(t=3.743, P<0.001) and FINS(t=3.442, P=0.001) in the observation group was better than those in the control group(P<0.05). The cycle ovulation rate(χ²=11.600, P=0.001) and pregnancy rate(χ²=6.620, P=0.010) in the observation group were higher than those in the control group(P<0.05). Conclusion The treatment of infertility patients with PCOS can improve the level of serum related hormones and fasting insulin level, thus improve the endometrial receptivity, and improve the ovulation rate and pregnancy rate.