In this study, we analyzed allelopathic effects of Pistacia chinesis Bunge on Oncomelania hupensis through triterpene sapogenin, a potential molluscicide. The snails were exposed to six different concentrations (0, 2, 5, 10, 20, and 40 mg/L) of triterpene sapogenin and under five periods (24 h, 48 h, 72 h, 96 h, and 120 h). The mortality of snails was positively correlated with the concentration of triterpene sapogenin and exposure time. The liver and intestine observation through transmission electron microscope displayed that 10 mg/L triterpene sapogenin caused apparent damages to the structure of O. hupensis liver. The esterase (EST) isozyme activity of O. hupensis treated by 10 mg/L triterpene sapogenins was higher than that of control between 24-48 h, then decreased after 72 h. It implicates that the extracted triterpene sapogenin from Pistacia chinesis Bunge is promising for controlling the snail. Meanwhile, it provides the foundation for constructing plant community of Pistacia chinesis to control O. hupensis.