Considering the navigation conditions of the entrance area in the downstream approach channel and the connecting section of the Fedongzi ship lock，we study the influence of the lock and dam dispatching mode on the flow characteristics of the entrance area and connecting section. A mathematical model is employed to study the flow conditions in the entrance area and connecting section when the lock and dam of the Fengdongzi navigation project are open in different positions and quantities. The results indicate that when the lock gates on the left bank are open at the same flow rate，the flow conditions in the entrance area and connecting section are more favorable to the safe navigation of ships；assuming the discharge condition of lock gates is met，the flow conditions are better when fewer lock gates on the left bank are open.