Objective:To observe the clinical efficacy of Yimu Gushen Decoction combined with active immunotherapy in the treatment of unexplained recurrent abortion. Methods56 patients with unexplained recurrent abortion were randomly divided into the treatment group and control group,28 cases in each group. The control group was treated with active immunotherapy,and the treatment group was treated with Yimu Gushen Decoction based on the treatment for the control group. The clinical efficacy,pregnancy outcome and medication safety were observed. The changes on the levels of immune indexes such as immunoglobulin G(IgG),immunoglobulin A(IgA),immunoglobulin M(IgM),complement C3(C3),complement C4(C4) and T lymphocyte subsets CD,4+, and CD,8+,and the levels of sex hormones such as progesterone and human chorionic gonadotropin(HCG) were compared.  Results:①The total effective rates were 89.3% in the treatment group and 64.3% in the control group,the clinical efficacy in the treatment group was obviously better than that in the control group(P,<,0.05). ②After treatment,there were statistically significant differences on the levels of IgG,IgA,IgM and C3 between the two groups,and the levels were obviously reduced in the treatment group compared with those in the control group(P,<,0.05). After treatment,the CD,8+, level in the treatment group was obviously higher than that in the control group,while the levels of CD,4+, and CD,4+,/CD,8+, were obviously lower than those in the control group(P,<,0.05). ③After treatment,there were statistically significant differences on the levels of HCG and progesterone between the two groups,and the levels were obviously increased in the treatment group compared with those in the control group(P,<,0.05). ④The abortion rate in the treatment group was obviously lower than that in the control group(P,<,0.05). ⑤No adverse reaction related to the intervention in this study was observed during the trial.  Conclusion:The active immunotherapy combined with Yimu Gushen Decoction in the treatment of unexplained recurrent abortion can improve the immune imbalance and sex hormone levels,reduce the risk of miscarriage as well as improve the pregnancy outcome,which is more safe.