OBJECTIVE To explore the mechanism by which Cuscuta chinensis flavonoids （CCF） promote decidualization and improve recurrent spontaneous abortion （RSA）. METHODS HTR-8/SVneo cells in logarithmic growth phase were randomly divided into blank group， lipopolysaccharide （LPS） group， CCF group， SGK2 inhibitor （GSK650394， abbreviated as “GSK”） group and CCF+GSK group. Each group was treated with the corresponding agents accordingly. HTR-8/SVneo cells with SGK2 knockdown were randomly divided into small interfering RNA of SGK2 （siSGK2） group and siSGK2+CCF group； additionally， blank group and LPS group were established； each group was treated with the corresponding agents accordingly. The cell survival rate， expression levels of WNK signaling pathway- and decidualization-related proteins and mRNAs， as well as mitochondrial membrane potential levels， were assessed in each group before and after SGK2 knockdown. RSA mice model was constructed and randomly divided into model group， CCF low-dose group， CCF high-dose group， GSK group， and combined dosing group， with 4 mice in each group. Other 4 normal pregnant female mice were selected as the control group. The number of implanted embryos， viable fetuses， and lost embryos in mice was recorded. The morphological changes of endometrium and decidualization were observed， and WNK signaling pathway- and decidualization-related proteins and mRNAs expressing levels as well as mitochondrial membrane potential levels were all detected. RESULTS Compared with the blank group， the cell survival rate， as well as the protein and mRNA expression levels of SGK2， WNK1， WNK4， prolactin， insulin-like growth factor- binding protein-1， oxidative stress responsive kinase 1， and Ste20-like proline-/alanine-rich kinase were significantly reduced in the LPS group （P＜0.05）； compared with the LPS group， the cell survival rate and the expression levels of the above- mentioned proteins and mRNAs were significantly increased in the CCF group， while the cell survival rate and the expression levels of the above-mentioned proteins and mRNAs were significantly decreased in the GSK group （P＜0.05）； compared with the CCF group， the cell survival rate and the expression levels of the above-mentioned proteins and mRNAs were significantly reduced in the CCF+GSK group （P＜0.05）. After knocking down SGK2， compared with the LPS group， the cell survival rate， red/green fluorescence intensity ratio， and the expression levels of the above-mentioned proteins and mRNAs were significantly reduced in the siSGK2 group （P＜0.05）； compared with the siSGK2 group， the cell survival rate， red/green fluorescence intensity ratio， and the expression levels of the above-mentioned proteins and mRNAs were significantly increased in the siSGK2+CCF group （P＜0.05）. The in vivo experimental results showed that CCF treatment can significantly improve the number of implanted embryos and viable fetuses in RSA model mice and reduce lost embryos， the expression levels of the above-mentioned proteins and mRNAs in endometrial tissue were significantly increased， and the red/green fluorescence intensity ratio was significantly increased （P＜ 0.05）； the combined dosing group could reverse the effect of CCF （P＜0.05）. CONCLUSIONS CCF can activate SGK2， up- regulate the WNK signaling pathway， promote endometrial decidualization， and improve RSA.