The killing effect on oncomelania hupensis by lixivium of pterocarya stenoptera , nerium indicum , rumex japonicus and their mixture was studied . differences of the snails mortality were studied also . the three kinds of plant material could kill the snail effectively both in spring and in autumn . but the mortality was different when the experiment is done in different seasons or with different lixivium . the effect in spring was better than that in autumn . n . indicum was the most effective among the three kinds . the effect by mixture was better than that by unitary material , and the effect by the mixture of the three kinds was better than that by two kinds . the variance analyses showed that the experiment could be modified , and some ingredients concentration in mixed lixivium could be reduced . the experiment was valuable in enhancing the power of killing the snail and saving plant material