Abstract: The simulation of the 12″2500Lb loaded underwater ball valve is carried out by using the finite element analysis software Ansys Workbench in this paper. The contact problem of sealing ratio and two contact surfaces of sealing pair is studied, and the sealing effect of the underwater ball valve is analyzed. Combining with the performance test of the underwater ball valve, rationality of the analytical method is verified. The relevant conclusions can provide a basis for optimization and product development of the underwater ball valves.