Based on the finite element software ANSYS, this paper builds up a 3D finite element model of monolithic lock chamber structure to conduct a simulation for the stress and deformation of this chamber structure in different conditions. The result shows that U-shape reinforcement prestressing technology used in depressed chamber structure is feasible, which not only provides solution to the problem of concrete crack, but also cuts down the cost of reinforcing bar. Thus it may serve as reference for the design of monolithic lock chamber.