〔Abstract〕 Objective To investigate the effect of silencing human leukocyte-associated antigen-G(HLA-G) expression in the chorionic trophoblast cell line JEG-3 cells under hypoxic conditions on the biological function of JEG-3 cells and through the hypoxia response pathway of endothelial PAS1 region protein 1(EPAS1)is involved in the molecular mechanism of preeclampsia under high altitude hypoxia.Methods The expression of HLA-G in JEG-3 cells was inhibited by transfection of small interfering RNA(siRNA). The JEG-3 cells after transfection were divided into four groups: normoxic control group, hypoxic control group, normoxic inhibition group, and hypoxic inhibition group.CCK-8 test and Transwell test were used to detect the proliferation and invasion ability of the cells in four groups; The effects of four groups of apoptosis and cell cycle were detected by flow cytometry; HLA-G and EPAS1 mRNA and protein expression levels were detected by real-time fluorescence quantitative PCR(qPCR) and Western blot. Results(1) Compared with the normoxic control group, hypoxic control group, normoxic inhibition group, and hypoxic inhibition group could reduce the proliferation activity and invasion ability of JEG-3 cells, and significantly increase the apoptosis rate. The hypoxic control group and hypoxic inhibition group also produced an obvious necrotic cell population; Under the condition of hypoxia, after reducing the expression of HLA-G, the cell necrosis rate was further aggravated; Whether under normoxia or hypoxia, inhibition of HLA-G expression caused the cells to be blocked in the G1 phase.(2) Compared with the normoxic control group, hypoxia control group, normoxic inhibition group, and hypoxia inhibition group decreased the expression of HLA-G protein, and hypoxia and inhibition of HLA-G had a synergistic effect; Hypoxia-inducible factors-2α(HIF-2α),vascular endothelial growth factor(VEGF) and endothelin-1(ET-1) protein expression could be added, inhibition of HLA-G decreased the expression of inducible nitric oxide synthase(NOS2). Conclusion In the hypoxic environment, silencing HLA-G may affect the biological behavior of trophoblast through the EPAS1 hypoxic response pathway and participate in the occurrence and development of preeclampsia.