To evaluate the predictive value of second-trimester maternal serum screening biomarkers for preeclampsia, we analyzed the second-trimester serum prenatal screening data of pregnant women, and identified preeclampsia diagnosis by hospitalization records. 198 cases who developed preeclampsia and 1171 healthy controls were included in this study. In 15˜20 gestational weeks, the cases who developed into preeclampsia had lower serum levels of uE3, uE3 MoM, but higher AFP MoM than controls, while no difference on AFP, fβ-hCG, and fβ-hCG MoM were found. A higher level of uE3 MoM was associated with a lower risk of preeclampsia (OR=0.35, 95% CI:0.19–0.65, P=0.0009). In addition, threshold effect was observed between preeclampsia and the MoM value of AFP and fβ-hCG, the risk of preeclampsia increased when the AFP MoM≥1.43(OR=1.93, 95% CI:1.20–3.11, P=0.0064), or fβ-hCG MoM≥2.31(OR=2.59, 95% CI:1.46–4.59, P=0.0012).