Owing to the downstream stilling basin of the barrage suffered destroy in Dongshan, the downstream river bed was cut and the water-level degraded, the downstream energy dissipater of barrage needs reinforcement and reconstruction. Through the hydraulic model test, based on the reinforcement and reconstruction of the current downstream stilling basin of the barrage, in order to ensure the safe operation of the sea-flood section at downstream stilling basin ，the auxiliary energy dissipaters suah as baffle block and baffle sill were set in sea-flood section. The research showed that, after setting the multistage baffle sills in the stilling basin downstream sea-flood section，the energy dissipation rate reached 50% at the sea-flood section, and ensured the flow of the stilling basin being connected more smoothly with the downstream river flow. The research achievement has been applied in engineering construction, and can be a reference for similar engineering design and operation.