Dafutan ship lock is located at the bank of Jiangxinzhou in the bifurcated reach. In view of the problem that the gate area of the downstream approach channel of the lock has a large oblique flow and return flow，and the confluence area of the two branches at the tail of the lock has a large oblique flow，so ships’ safe navigation can not be guaranteed，we put forward improvement measures，and all regulation schemes are verified by adopting the 180 normal overall hydraulic physical model. The results show that the recommended measures of prolonging the length of the downstream navigation wall of the lock and constructing a new downstream dam can effectively improve the navigation flow conditions of the downstream lock.