Abstract: In this paper, the compatible dynamic finite elements with diagonalized consistent mass matrix are studied. In previous papers^[1,2], the author studied the dynamic finite elements with diagonalized consistent mass matrix, but all of them are incompatible elements. In this paper,the compatible form functions are obtained not only for the tetrahedron elements, but also for the triangular ring elements, with diagonalized consistent mass matrices. This kind of finite elements can be used for the treatment of impact problems, vibration problems, and problems involving time coordinates, including the linear and nonlinear equations.