For hydro-junction with constructed ship lock,constructing second lock can greatly improve the lock capacity.Being affected and restricted by topography,river regime and the constructed hydraulic structures,the outer boundary condition of the expanded ship lock,especially the navigable flow condition of the entrance area,is usually complex.Taking the second ship lock project of Dayuandu navigation-power junction as an example,we study the layout and improving measures of the entrance area of the expanded ship lock under complex condition,and propose a scheme combining the engineering measures and the control measures. The scheme can solve the entrance area problem and save a lot project investment while meeting the demands of ship lock operation.The research result can provide reference for similar projects.