Baishiyao hub locates on the Beijiang River main stream，25 km upstream from Yingde city. It is the third cascade of the Beijiang River. To improve the passage capacity of the ship lock，the length of the lock chamber of the Baishiyao first line ship lock is extended from 140 m to 220 m. The effective scale of first-line ship lock design is 220 m×23 m×4.5 m（length×width×doorsill water depth）. This paper studies the flow condition of the entrance gate of the downstream approach channel by establishing a 1:100 scale physical model. Through the overall hydraulic model test，the paper puts forward the improvement measures of the navigation condition in the entrance area of the downstream approach channel. The study shows that measures such as the excavation of Sanbanzhou and the addition of linear dikes are effective to improve the navigation condition at the entrance of the downstream approach channel.