Abstract: Objective To investigate the effect of SGK1 expression in decidual stromal cells (DSCs) on Treg/Th17 balance of peripheral blood lymphocytes in women of reproductive age. Methods DSCs from normal early pregnancy women were isolated and cultured, and DSCs were identified by immunocytochemistry, then passed to the third or fourth generation. The peripheral blood lymphocytes (PBLC) of women were isolated and cultured in vitro, and co-cultured with each group DSCs. PBLC were divided into 5 groups. 1. Control group, 2. Co-culture group, 3. SGK1 activator group, 4. SGK1 inhibitors group, 5. Co-stimulatory group. The expression levels of SGK1 proteins were detected by Western blotting. The expression levels of SGK1 mRNA were detected by RT-PCR. The proportion of Treg and Th17 cells was measured by flow cytometry. Results Western blotting and RT-PCR results indicate that the expression levels of SGK1 mRNA were significantly higher in SGK-activated group than in the other groups (P < 0.05). Compared with the co-culture group, the levels of SGK1 mRNA both in the SGK1 inhibitor group and the Co-stimulation group were exhibited decreasing trends (P < 0.05), especially lower in the inhibitor group (P<0.05) . Meanwhile, flow cytometry showed that the ration of Treg cells /Th17 cells in the SGK1 activation group was significantly higher than that in the other four groups (P < 0.05). In agreement with the data, the proportion of Treg in in the co-culture group is dramatically increase than control counterpart. Compared with the co-culture group, the percentage of Treg subsets in the SGK1 inhibitor group and the co-stimulus group was obviously reduced (P < 0.05), and the decrease was more significant in the SGK1 inhibitor group. Conclusion SGK1 expressed by DSCs in early pregnancy can affect the proportion of Treg subgroup and Th17 subgroup in peripheral blood lymphocytes。