The Dayuandu navigation power junction is designed to build up the fish path,which is limited by the general layout conditions of the hub.The entrance of the fish way is arranged in the tail water of the power station,the construction is difficult and the investment is big,and there is a serious risk of safety.To ensure the safety,save the investment and meet the requirements of the fish path,a two-dimensional hydrodynamic numerical model is established using SMS-RMA2 model to simulate and get the flow field map in a certain range under different operating conditions in the downstream of the axis of the hub dam and to provide a reliable reference for the determination of the proper fish path entrance in slightly curved braided reach where the dam is built.In order to improve the effect of the fish path,it is suggested to set up the electric fish screen and the sound & light of sprinkler water on the upper side of the inlet of the fish path,so as to help fish find the entrance of the fish path as early as possible.