To investigate the correlation between the expression of HtrA4 in placenta tissue of women with severe preeclampsia and their perinatal outcomes. Methods: 69 pregnant women with severe preeclampsia were selected in study group and 50 normal pregnant women were selected in control group. The experience of HtrA4 in peripheral blood and placenta tissue of all women were detected. The maternal pregnancy outcomes and the experience differences of HtrA4 in placenta tissue of women in the two groups were analyzed. Pearson correlation coefficient was used to describing the correlation between HtrA4 expression in placenta tissue and neonatal birth weight, umbilical hemodynamic parameters, such as the ratio of fetal umbilical artery systolic pressure to diastolic pressure (S/D), pulsation index (PI), resistance index (RI). Results: The expressions of HtrA4 in the serum and placenta of women with severe eclampsia group were significant higher than those of women in the control group (P<0.05). The expressions of HtrA4 in the serum and placental tissues of women with adverse pregnancy outcomes and poor perinatal outcomes were significant higher than those of normal pregnancy women (P<0.05). There was a negative correlation between HtrA4 expression in placental tissue and neonatal birth weight (r=-0.478, P<0.05). There was a positive correlation between HtrA4 expression in placental tissue and S/D value, RI and PI (r=0.476, 0.540, 0.650, P<0.05). Conclusion: The expression of HtrA4 in placenta tissue of women with severe preeclampsia has up-regulate significantly, which is closely related to pregnancy outcomes and perinatal outcomes.