To solve the problem that the mismatch between the bottom elevation of Sanjiang approach channel and the threshold elevation of No.2 ship lock，it is necessary to implement the promotion construction project of Sanjiang downstream channel at Gezhouba Dam.The project can effectively improve the throughput of ship locks of Gezhouba Dam in dry season.Considering that ship locks of Gezhouba are currently in saturated operation，we propose three representative construction schemes on the basis of full investigation to reduce the possible negative influences of project construction on navigation，and proof in detail.The results show the all-cofferdam dryland construction scheme is the best one in no doubt if taking into account of various factors such as navigation safety and capacity，construction schedule and so on，while the wetland construction scheme is conversely the best one to uninterrupt the economic and social life along the Yangtze River.