Objective To determine the effective accumulated temperature of Oncomelania hu-pensis during the period of development of generations in the natural environment. Methods The snails, Oncumelania hupensis, were raised in natural breeding site, the developing duration and accumulated temperature for .snails' development from eggs to adult that began to lay eggs were estimated based on the formula T=?(Ti-C). Results The average developing duration was (334.22?7. 52) days, average accumulated temperature was (5 821.38?70.05) day degree, and average effective accumulated temperature was (3 846.28?32. 59) day degree. Conclusion The method to estimate the effective accumulated temperature is quite accuracy, which provides theoretical parameters in developing the prediction model on transmission of schistosomiasis japonica affected by weather warming.