Abstract： Objective： To observe the clinical effect of the therapy of modified Shoutai pills combined with low molecular weight heparin calcium injection on prethrombotic state in patients with polycystic ovary syndrome(PCOS) complicated with recurrent spontaneous abortion. Methods：A total of 150 PCOS patients with kidney deficiency and blood stasis syndrome and complicated with recurrent spontaneous abortion were selected and randomly divided into the western medicine group，the Chinese medicine group and the combination group， with 50 cases in each group. The western medicine group was given low molecular weight heparin calcium injection， the Chinese medicine group was given modified Shoutai pills， and the combination group was given low molecular weight heparin calcium injection combined with Shoutai pills. All groups were treated for four courses， with seven days being a course. The clinical effects in the three groups were compared. Before and after treatment， the changes of serum β- human chorionic gonadotropin(β-HCG)，estradiol(E2)，progesterone(P)，coagulation-fibrinolysis indexes，including plasma prothrombin time(PT)，thrombin time(TT)，activated partial thromboplastin time(APTT)，plasma fibrinogen (FIB)， D- dimer(D- D)， plasminogen activator inhibitor- 1(PAI- 1)， and antithrombin Ⅲ (AT- Ⅲ)， and uterine artery blood flow parameters， including bilateral peak systolic velocity/diastolic velocity(S/D)， pulsatility index(PI) and resistance index(RI)， were compared between the three groups. Results： After treatment，during the 10th to 11th weeks of pregnancy，the levels of β-HCG，E2 and P in the three groups were increased when compared with those before treatment， differences being significant； after treatment，during the 10th to 11th weeks of pregnancy，the above three levels in the combination group were higher than those in the western medicine group and the Chinese medicine group，differences being significant(P＜0.05). After treatment， during the 10th to 11th weeks of pregnancy， the values of PT， TT， APTT and ATIII in the three groups were increased when compared with those before treatment，and the values of D-D，FIB and PAI- 1 were decreased，differences being significant(P＜0.05)；after treatment， during the 10th to 11th weeks of pregnancy，the values of TT，APTT and ATIII in the combination group were higher than those in the western medicine group and the Chinese medicine group，and the values of D-D， FIB and PAI-1 were lower，differences being significant(P＜0.05). After treatment，during the 10th to 11th weeks of pregnancy， the values of S/D， PI and RI of bilateral uterine arteries in the three groups were decreased when compared with those before treatment， differences being significant(P＜0.05)； after treatment，during the 10th to 11th weeks of pregnancy，the above three values in the combination group were lower than those in the western medicine group and the Chinese medicine group，differences being significant(P＜0.05). After treatment， the total effective rate was 70% in the western medicine group， 72% in the Chinese medicine group and 90% in the combination group. The total effective rate in the combination group was higher than that in the western medicine group and the Chinese medicine group， differences being significant(P＜0.05). Conclusion：The therapy of modified Shoutai pills combined with low molecular weight heparin calcium injection for prethrombotic state in PCOS patients complicated with recurrent spontaneous abortion can effectively improve the plasma viscosity， reduce the abnormal resistance of uterine artery blood flow，improve the endometrial receptivity，restore the intervillous blood flow，ensure the normal development of the fetus，and increase the success rate of fetal protection.