An optimum design of check valve cores helps to improve the life and service effect of the valve body. It is found that modifying valve clacks and cores to change the flow surface structure can effectively improve the overall flow characteristics of the water body at the valves by simulating the working process of check valves with different flow surface structure. Based on the technological requirements of valve body processing and the constraints of simulation boundary conditions, an optimal design can be established of the valve core length and valve clacks, thus obtaining a new structure that helps to reduce the swirling and jetting phenomena as well as the effect of water flow stratification. Subsequent experiments verify that the optimized structure is characterized with a better performance.