The pit for the culvert of the fish way entrance is extremely large,beside which power station’s typical buildings and Sanmenqu lock chamber are built,and the approaching road is built above the culvert.In view of the problems such as narrow construction site and multiple limitations,we study the type of the supporting structure and corresponding application conditions.Conducting the detailed design of the brace type structure,double-row pile type structure,and the construction scheme of jacking box culvert,and carrying out the scheme comparison and selection based on the qualitative analysis and reviewing calculation,we determine to adopt the twin-bracing scheme for implementation.Meanwhile,the observation requirement and matters needing attention are also presented.