This paper expounds the model test of the spillway of Taihu reservoir，reviews the rationality of the original design scheme，and puts forward the optimization design scheme.The results of the model test can be seen that the spillway spillcapacity meets the design requirements，but the nasal pickling distance is too short，the water tongue air energy dissipation is not sufficient， the size of the punch is large， and the downstream is seriously washed.By increasing the size optimization of angle dingling and anti-arc radius，the pattern of pick-up is obviously improved，and the stability of dam body and shore slope will not be affected，indicating that the design is reasonable and has some guiding significance for similar projects.