Due to the influence of the river topography，large-scale oblique flow and cross flow，which threatens the safety of shipping seriously，will appear in the ship lock entrance area when the downstream navigable water level of Honghua multi-line ship lock is low. According to the results from the hydraulic model study of scale 1100 and self-propelled ship model test，we take comprehensive measures such as deepening trench diversion in large area，lowering sandbank elevation in obstructive sections，lengthening the separation levee length and making divider by backfilling according to the characteristics of flow pattern at the low navigable water level，by which the velocity of vertical flow，horizontal flow and backflow in the entrance area is reduced effectively. It is verified that the optimization measures not only meet the navigation requirements at the downstream low water level，but also effectively increase the maximum navigable flow and navigation efficiency of the ship lock. It is shown that the ship handling parameters are all within the required range by the test results of ship model. The research results can be used as reference for related pivotal projects.