The objective of this study is to investigate the antiabortive effects of Quercetin and Bornvl Acetate and their immunological modulation at maternal-fetal interface. Lipopolysaccharide (LPS) was injected via tail vein to induce abortion in mice which received Quercetin and Bornvl Acetate at days 4–7 of gestation. Uterine CD4+/CD8+ T lymphocytes and IFN-γ/IL-4 of each group (n=10) were detected by immunohistochemistry and enzyme-linked immunosorbent assay, respectively. The ratio of CD4+/CD8+ increased significantly (P<.01) in the uterus of LPS-induced abortion mice. In the Quercetin and Bornvl Acetate pretreated mice followed by LPS administration, the ratio of CD4+/CD8+ dropped to 0.562±0.021, lower than that of LPS-abortion group (P<.01). The mean value of IFN-γ/IL-4 in LPS-treated mice was 0.310±0.066, higher than that of Quercetin and Bornyl Acetate group. The results indicate that Quercetin and Bornyl Acetate have an antiabortive effect through modulation of immunological balance at maternal-fetal interface.