Due to the difficulty of dynamics modeling in fish surrounding by the fluid, little progress has been made in the design of the current pectoral locomotion. With the rapid development of the high performance computers and numerical methods, finite element modeling applied to explore the hydrodynamics of the fish has become a hot topic recently. The kinematics modeling is usually the first step in sovling the problem. Therefore, the kinematics modeling of pectoral locomotion in fish is proposed. The pectoral locomotion is simulated with the physical character and kinematic parameter, and the kinematic formula of the pectoral locomotion in batoid fish is simplified. Along with the boundary condition of the above kinematic formula, the finite element modeling in Cownose Ray is finally simulated in order to study the kinematics. The simulation modeling, compared with the observation results, is proved to be valid.