Objective:To observe the expression of IL-15 and IL-22 in decidua and peripheral blood and the effect of Bushen Huoxue Recipe on it in patients with unexplained recurrent spontaneous abortion (URSA). MethodsTrial 1:30 patients were enrolled and assigned into the experimental group (patients with URSA and pregnancy failure) and the normal control group (patients with normal pregnancy and induced abortion), 15 patients in each group; and the mRNA levels of IL-15R and IL-22R in decidual tissues of the subjects in the two groups were determined by RT-PCR. Trial 2:60 patients with URSA and re-pregnancy were randomly assigned into the treatment group and the control group, 30 patients in each group; and the treatment group was treated with Bushen Huoxue Recipe + dydrogesterone, while the control group was treated with dydrogesterone. Both groups were treated for 4 weeks, and the short-term efficacy and pregnancy outcome were observed. Changes in the levels of IL-15 and IL-22 in peripheral blood were compared.  Results:① RT-PCR showed that the expression of IL-15R and IL-22R in decidual tissues of subjects in the experimental group was significantly higher than that in the normal control group (P<0.05). ② There was no significant difference in the levels of IL-15 and IL-22 between the groups before treatment (P>0.05). The levels decreased significantly in both groups before and after treatment (P>0.05). After treatment, the levels were significantly lower in the treatment group than in the control group (P<0.05). ③ The total effective rate was 93.33% and 73.33% in the treatment group and the control group respectively; and the short-term efficacy in the treatment group was significantly superior to that in the control group (P<0.05). ④ The abortion rate was 6.67% and 26.67% in the treatment group and the control group respectively. It was significantly lower in the treatment group than in the control group (P<0.05).  Conclusion:The occurrence of URSA may be related to the high expression of IL-15R and IL-22R in the decidua. At the same time, Bushen Huoxue Recipe significantly down-regulates the levels of IL-15 and IL-22 in peripheral blood of patients with URSA. The mechanism of action may be regulation of maternal immune tolerance during pregnancy, thereby facilitating maintenance of pregnancy and reducing the incidence of abortion.