In this study, the expression of IL-24 at maternal-fetal interface and the roles in extravillous trophoblast (the TEV-1 cell line) invasion were examined. Immunohistochemistry was used to detect the expression of IL-24 in villi and decidual tissue. The proliferation of TEV-1 cells under the effect of IL-24 was measured by MTT assay. The invasiveness of TEV-1 cells under the effect of recombinant IL-24 (rhIL-24) was examined by transwell system. Immunohistochemical detection showed that IL-24 was expressed in the villi and decidual tissue, and distributed in villous column, trophoblasts, stroma and blood vessels. The proliferation of TEV-1 cells was not inhibited by rhIL-24 of various concentrations. The examination of invasion in vitro showed that rhIL-24 could inhibit the invasion of TEV-1 cells in a concentration-dependent manner. The results suggested IL-24 could inhibit the invasion of TEV-1 cells. Therefore, IL-24 produced by maternal-fetal interface in human first trimester pregnancy may influence the invasion of trophoblasts and is involved in normal pregnancy.