Based on the analysis of the restricting and influencing factors for the construction scale and plane layout of the Yuxi Shiplock expansion and reconstruction project, the annual freight volume and the ship throughput were forecasted and the construction scale, the lock position and the general layout of the project were determined. A two-dimensional hydrodynamic model was established to simulate the navigation flow conditions of the approach channel and the entrance area in the upstream of the regulating sluice and the Yuxi Shiplock under various operating conditions. According to the calculation results, the local route alignment of the upstream entrance area and the connecting section is adjusted. Countermeasures reducing the flow velocity and ensuring the navigation safety are proposed, including dredging at the north side of the two curved sections, enlarging the cross-section of the water flow, reducing the flow velocity. The construction scale, lock position and general plane layout of the ship lock determined by comprehensive analysis are well coordinated with many contradictions. The research result shows that the in-situ reconstruction scheme is feasible and the design idea can be referred to similar projects.