The approach channel of the lock in the downstream of the curved reach is not only restricted by the bend flow，but also affected by the bending water from the broadening riverbed. The energy of reflux and oblique nearby the entrance area is great and with a large range，and the flow condition is unfavorable. Thus it is difficult to meet the requirement of safe navigation. Based on the hydraulic principle and flow motion law and combining with the variation characteristics of the curved reach，we put forward the engineering measure that setting the pier for deflecting flow on the outside of approach channel nearby the entrance area，and adopting the entity and open-piled guide wall. Model test results show that this measure can adjust the flow direction，construct the water area of slow flow，completely eliminate the reflux and oblique，improve the navigable flow condition，and ensure the safe navigation.