Taking a lock on the upstream of the Yangtze River for example,we simulate the separate lock with shear keys and separate lock with flat joints by software ANSYS.In this process the Coulomb friction model is used as the tangential contact constitutive model and it is thought that the joints can pass the contact pressure,but not the pull.We investigate the joints opening size,the vertical displacement and stress state of structure,and analyze comprehensively the impact of the shear keys.Studies show that comparing with flat joints model,the joints opening size of the shear keys model is small,and the integrity property is good；the displacement of the chamber wall and floor is continuous；the stress distribution of the foundation below the floor is uniform.Increasing the shear keys’ angle is helpful in reducing the joint opening and uniform the ground stress distribution.