To explore the clinical effect of tanshinone combined with GnRH-a pituitary down regulation for treating women with polycystic ovary syndrome (PCOS) during freeze thawing embryo transplantation. Methods: 150 women with PCOS during freeze thawing embryo transplantation (FET) were divided into group A (women given polycystic only), group B (women given GnRH-a pituitary down regulation only), and group C (women given tanshinone combined with GnRH-a pituitary down regulation). The levels of serum reproductive hormone, and glucose and lipid metabolism index, the endometrial receptivity, and the clinical pregnancy outcomes of the women were compared among the three groups. Results: There were no significant different in the levels of serum basics reproductive hormone, and glucose and lipid metabolism index of the women among the three groups (P＞0.05). The levels of serum follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), and testosterone (T) of the women on the endometrial transformation day and 1 day before FET in group C were significantly lower than those of the women in group A and group B (P＜0.05). The levels of fasting blood glucose (FBG), cholesterol (TC), triglyceride (TG), and low density lipoprotein (LDL) of the women in group A and group C on the endometrial transformation day had decreased significantly (P＜0.05), and the levels of FBG, TC, TG and LDL of the women in group C were significantly lower than those of the women in group B (P＜0.05). The endometrial thickness, the ratio of endometrial type A, and the clinical pregnancy rate of the women in group C on the ET day were significantly higher than those of the women in group A and group B (P＜0.05). Conclusion: Tanshinone combined with GnRH-a pituitary down-regulation can further improve metabolic abnormalities of the women with PCOS, reduce their serum androgen level, increase their endometrial receptivity, and improve their pregnancy outcomes.