Preeclampsia (PE) is a severe complication specific to pregnancy, characterized by the onset of hypertension after 20 wk of gestation, often accompanied by proteinuria and damage to important maternal organs. The abnormal invasive function of trophoblast cells leads to impaired remodeling of uterine spiral arteries, shallow placental implantation, and inadequate uteroplacental perfusion, which is one of the important factors in the development of PE. This study aimed to explore key molecules that affect the invasive and migratory functions of trophoblast cells. The study found that thrombospondin-4 (THBS4) expression in the placental tissue of preeclampsia decreased compared with normal pregnancy and was localized in trophoblast cells. Knocking down THBS4 expression inhibited the transforming growth factor (TGF)-β1 signaling pathway in HTR-8/SVneo cells and reduced cell proliferation, migration, and invasion abilities. The knockdown effect of THBS4 could be reversed by TGF-β1 agonist, hyclate. In conclusion, the results of our study indicate that THBS4 may regulate the biological functions of trophoblast cells through the TGF-β1 signaling pathway and may play an important role in placental vascular development. THBS4 may regulate the biological functions of trophoblasts through the TGF-β1 signaling pathway and may play an important role in placental vascular development.