Control of infection by Schistosomiasis, which causes a severe health problem in human, has been a challenging task for most endemic countries in the tropics and subtropics. Schistosomiasis remains a public health concern in China after a concerted effort in the past decades. Oncomelannia hupensis, the only intermediate host of Schistosome, is regarded as the weakest link in the life cycle of Schistosome. Killing O. hupensis can control the epidemic of Schistosomiasis in public water sources. Plant molluscicide is considered as the best reagent as judged by public safety, financial cost, and environmental protection. We used Cinnamomum camphora here in this experiment. Extract of leaf, barks of root and shoot of C. camphora were used at 4 concentrations(1%, 0.5%, 0.1% and 0.05%) (water and 1mg/L Niclosamidum as the control)in the experiment against snails O. hupensis. The mortality of snails was investigated. The activities of catalase (CAT), peroxidase (POD) and TEM ultralstructure of O. hupensis liver cell were analyzed in the experiment. The results showed that the molluscicidal effect of the lixivium of C. camphroa against O. hupensis is excellent. The mortality of the snails correlated with the concentrations of the lixivium and the time of treatment. The mortality of the snails treated with water extracts from leaf, barks of root and shoot of C. camphora in 4 concentrations in 120 h was up to 100%, which is similar with that of 1mg/L Niclosamidum. The molluscicidal activity order of different parts from C. camphroa against O. hupensis ranks: root bark > stem bark > leave. Treatment with 0.5% leaf water extract induced a significant increase of the activities of CAT and POD in the early period time points (48 h and 73 h respectively) followed by a dramatic decrease. Further more, 0.5% water extract of leaf causes a marked damage in liver as judged by the TEM ultrastructure analysis. For example, 48 h treatment with 0.5% leaf water extract caused a slight damage to nuclei of hepatocytes of the snail, which manifested as slightly nuclei swelling; loosed chromatin; reduced number of mitochondria and even condensed or ruptured mitochondria; expanded or fragmented reticulum cavity of rough endoplasmic in cytoplasm. The damage to hepatocytes was further exaggerated 72 h after treatment: broken nuclei of hepatocytes; reduced chromatin mass; organelles cavitation; vague and broken mitochondria Cristae. These hepatocytes were filled with dense bodies and different types of gas vacuoles. The cell membrane was raptured. We conclude that the plant C. camphroa demonstrates a strong molluscicidal activity in a peroxide-dependent manner, which damages the organelles of hepatocytes. Thus, C. camphroa will be better plant resource in controlling the snails in ecological projects.