Objective To analyze the effect of vitamin D supplementation on ovulation induction in infertile women with polycystic ovary syndrome (PCOS) and 25(OH)D deficiency. Methods A total of 72 PCOS infertile women with 25(OH)D deficiency in our reproductive center from January 2019 to December 2019 after vitamin D treatment were selected as observation group, and 59 infertile PCOS women without vitamin D treatment were selected as control group. The two groups were treated with clomiphene citrate (CC)/CC + urotropin. The general data, cycle ovulation rate, biochemical pregnancy rate, clinical pregnancy rate and OHSS incidence rate in two groups were collected. Results there were no significant differences in age, body mass index (BMI), infertility years, basal hormone levels [estradiol, progesterone, follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone)] and basal endometrial thickness between the two groups (P＞0.05). The ovulation rate (χ2=4.28, P=0.039) and clinical pregnancy rate (χ2=5.17, P=0.023) in observation group were significantly higher than those in control group, but there was no significant difference in biochemical pregnancy rate and OHSS incidence between the two groups (P＞0.05). Multivariate logistic regression analysis showed that normal serum 25(OH)D level was an independent predictor of ovulation cycle(OR=0.041, 95% CI:0.003-0.629, P=0.022). Normal serum 25(OH)D level (OR=0.563, 95% CI: 0.420-0.755, P＜0.001) and basal testosterone level (OR=1.370, 95% CI: 1.012-1.854, P=0.042) were independent predictors of clinical pregnancy in ovulation cycle. Conclusion Vitamin D supplementation can improve the ovulation rate and clinical pregnancy rate of PCOS women with infertility and 25(OH)D deficiency. Normal serum 25(OH)D level is an independent predictor of ovulation cycle, and normal serum 25(OH)D level and serum basal testosterone level are independent predictors of clinical pregnancy in ovulation cycle.