The Gedi junction in the Changshan River is located in the middle of the “S”-shaped curved river section. The upstream approach channel is on the concave bank of the river channel，the downstream approach channel is on the convex of the bank，and the flow condition of the approach entrance area and the connecting section is complex，so the velocity index cannot satisfy the requirements of safe navigation. Based on the physical model with a scale of 1：80，we study the navigable flow characteristics of the approaching entrance area and the connecting section of the upstream and downstream approach channel and propose the optimized layout scheme. The results show that reasonably dredging the convex bank along the channel and properly regulating the route layout of the approach channel can improve the navigable flow conditions of the approach entrance area and the connecting section，so that the velocity indexes of the approach entrance area can meet the demand of codes concerning the navigable flow，which achieves safe navigation of ships and normal operation of the hydro-junction.