To observe the effect of pachyman on the pregnancy outcomes of mice with recurrent spontaneous abortion (RSA), and to explore its mechanism. Methods: Female CBA/J mice and male DBA/2 mice were mated according to the ratio of 2:1 to establish RSA model. They were randomly divided into model group, low, medium and high dose pachyman group, and positive control group. Female CBA/J mice and BALB/c mice were mated according to the ratio of 2:1 to establish normal pregnancy model in control group. On the first day of pregnancy, the female mice in control group and in model group were given distilled water by gavage, the female mice in the low, medium, high pachyman groups and positive control group were given 50, 100, 200 mg pachyman and 156 mg/kg progesterone capsules dissolved in distilled water by gavage, the volume of gavage was 0.1 ml/10 g, once a day for 16 consecutive days. The numbers of embryo implantation and absorption were observed and recorded to evaluate their pregnant situation. The spleen and thymus indexes of mice in these groups were calculated. The ratios of Th17, Treg, CD4+ and CD8+ T lymphocytes in uterine tissue of mice in these groups were detected by flow cytometry. And the levels of IL-17, IL-22, IL-10 and TGF-β were detected by kits. Results: Compared with those of mice in the control group, the rate of embryo loss, the ratio of Th17 cells, the ratio of Th17/Treg, the expression of IL-17 and IL-22, and the number of CD8+ of mice in the model group were significant higher, but the index of spleen and thymus, the ratio of Treg cells in uterus, the expression of IL-10 and TGF-β, the number of CD4+, and the ratio of CD4+/CD8+ of mice in the model group were significant lower (all P<0.05). Compared with those of mice in the model group, the rate of embryo loss, the ratio of Th17 cells, the ratio of Th17/Treg, the expression of IL-17 and IL-22, and the number of CD8+ of mice in low, medium and high dose pachyman groups decreased in turn (P<0.05), but the index of spleen and thymus, the ratio of Treg cells in uterus, the expression of IL-10 and TGF-β, the number of CD4+ and the ratio of CD4+/CD8+ increased in turn (P<0.05), and the change trend of above indexes of mice in positive control group was consistent with that of mice in low, medium and high dose pachyman groups. Conclusion: Pachyman can improve the adverse pregnancy outcomes of mice with RSA, which may be related to the regulation of Th17/Treg immune cell balance of their uterus tissue.