Through numerical simulation and model test on diversion tunnel discharge of water conservancy project in Aertash of Xinjiang,the paper optimized the shape of stilling pool, and compared water level line, energy dissipation, the maximum underflow speed and the flow pattern of tailwater canal of the optimization scheme with that of original design scheme. The results show that after the optimization, the maximum water depth decreased 2.05 m in the stilling basin, the energy dissipation ratio increased by 12%, the maximum underflow velocity reduced by 28%, and the velocity in tailwater canal decreased by 66.7%.The hydraulic characteristics indicators show that the stilling pool after optimization performs a better characteristics compared with that of the original design scheme.