Objective To observe the effect of praziquantel external cream preventing skin invasion from Schistosoma cercariae.Methods Experimental mice were spread with 1％ or 2％ praziquantel external cream on the shaved abdomen skin respectively before infection,control group mice were treated with free-chloride water the same way.The instant contact and delay contact infection experiment with free-chloride water washing methods were used to carry out the infection of schistosome cercaria.The appearance and Schistosoma eggs of the mice liver in both experimental and control group were observed under microscope.Meanwhile,the number of Schistosomajaponicum worms was compared.The number of adult worms between the experimental group and the control group was compared by analysis of variance,the number of adults between two kinds of experimental methods was compared using t test.Results The liver surface of experimental group mice was smooth.Eggs and worms were not found.However,the livers of control group mice were dark in color with nodules of different degree on surface,scattered or piles of schistosome eggs were found under microscopy,and various number of adult Schistosoma were collected.There were 6.17±3.86 and 9.50±3.98 adults found in the control group of instant contact infection experiment and delay contact infection experiment respectively.There was significant difference of adult Schistosoma number between experimental and control group at two different methods(F=14.316,P＜0.01 ; F=20.990,P＜0.01).There was no significant difference of adult Schistosoma number between two control groups(t=-1.159,P＞0.05).Conclusion Praziquantel external cream has efficiency on preventing Schistosoma cercariae from skin invading.