In view of the limited draft of the Gezhouba Dam Sanjiang ship locks during the dry season，this paper puts forward a thought of excavation extension and a development scheme for Gezhouba Dam Sanjiang downstream navigable channels that take into account the construction of the new waterways of the Three Gorges Hydro-junction. Comprehensively considering the representative ship type in the new channel design and the traffic flow in the Sanjiang navigable channels，this paper analyzes and calculates the scale requirements of the Sanjiang navigable channels and investigates the improvement degree of the passing capacity of the Gezhouba Dam Hydro-junction and the impact on navigation benefit after the deepening of the Sanjiang downstream navigable channels. The implementation of the project will increase the annual throughput of the Gezhouba Dam Hydro-junction by approximately 6.698 million t and yield a direct economic benefit of 335 million CNY/a.