Objective To explore the clinical value of preparatory treatment using estradiol valerate and mifepristone before the curettage of the late small missed abortion.Methods One hundred and twenty patients with late small missed abortion were randomly divided into two groups:pretreated group(n =660) and control group(n =60).Women in the pretreated group were given 5 mg of Estradiol Valerate 3 times/day and 25 mg of Mifepristone twice/day for 3 days each before conducted curettage on the fourth day.While for the control group,curettage was done directly.The condition of operation and the occurrence of short-and long-term complications were compared between the two groups.Results Compared with the control group,the pretreated group had a significant shorter operation duration[(8.6±2.7) rnin vs.(10.5±3.4) min,t =3.390,P =0.001]and less blood lose during operation[(47.5±18.3) ml vs.(61.8±20.5) ml,t =4.031,P ＜ 0.001].In terms of complications,the rates of incomplete curettage[(0 vs 13.3％,x2 =6.563,P =0.010],artificial abortion syndrome(3.3 ％ vs 15.0％,x2 =4.904,P =0.027),the cervical canal adhesion/Asherman' s syndrome(0 vs 11.7％,x2 =5.461,P =0.019),and the vaginal bleeding duration[(7.5±2.7) days vs(8.7±3.4) days,t =2.141,P =0.034]in the pretreated group were significantly lower than those in the control group.The average recovery time of menstruation after operation in the pretreated patients was significantly shorter than that in the control group[(30.5±9.3) days vs.(35.5±7.4) days,t =3.259,P =0.002].Contusion Estradiol valerate and Mifepristone as a preparatory treatment before the operation can help reduce the occurrence of complications and side effects in the late small missed abortion curettage and is helpful for the patients' recovery,thus worth wide clinical application.