Objective: To investigate the effect of triptolide(TP) on the proliferation,apoptosis and the expression of BCL-2/BAX of human choriocarcinoma cell line JAR in vitro. Methods:Human choriocarcinoma cell line JAR was cultured. After the treatment with triptolide, MTT assay was used to detect the inhibitive effect of triptolide on cell proliferation; TUNEL assay was exploited to determine the level of cell apoptosis; Western blot was used to observe BCL-2/BAX expression. Results: TP could inhibit the proliferation of cell line JAR. The inhibition effects were concentration and time dependent. TP could affect the apoptosis of cells, and the difference was statistically significant with control group(P < 0. 05). PCR and Western blot showed the mRNA and protein levels of BCL-2 were significantly decreased, and the mRNA and the protein levels of BAX were significantly increased after exposure to TP, compared with control group(P < 0.05). Conclusion:Triptolide could inhibit the proliferation and induce apoptosis of JAR cells. The apoptosis mechanism involves the down-regulation of BCL-2 protein and up-regulation of BAX protein.