Abstract: Objective: To study the changes of the expression of placental growth factor (PLGF) in placenta and soluble fms-like tyrosine kinase-1 (sFlt-1) in serum of patients with severe pre-eclampsia.Methods: Twenty normal pregnant women (control group) and 32 women with severe pre-eclampsia were selected.The expression level of PLGF in placenta among the two groups was determined by immunohistochemistry S-P mothod,and the results were analyzed with imagepro plus analysis software.The serum sFlt-1 level of the two groups was measured by ELISA.Results: The expression of PLGF in the trophoblast of patients with severe pre-eclampsia was lower than that in the control group (P<0.05),while the serum sFlt-1 level was significantly higher than that of the control group (P<0.01).Conclusions: The PLGF in placenta and sFlt-1 in serum may be related to the etiology of pre-eclampsia.The level of sFlt-1 in maternal serum may serve as a diagnostic marker of pre-eclampsia.