A network preventing oncomelania diffusion is easily blocked by floating materials in a river to reduce the discharge capactity. Therefor, the network needs to be often cleaned and replaced, which causes the inconvenience to the operation management of practical engineering. Placing the network net cage intercepting oncomelania can solve the abovementioned problem. On the basis of model test, the intercepting oncomelania effects of netcasge are compared under the condition of both ina rapid follow and slow flow. The study results show that the net casge intercepting oncomelania has a better effect to prevent snail diffusion, and the channel dont be clogged to let the flow smoothly. The feasibility of the net cage intercepting sail is preliminarily tested.