With the gradual development of the Marine field, the underwater robot has gradually entered people's perspective. However, the structure and control of the current amphibious robot is too complex, and most of them need to switch two sets of structures to adapt to the amphibious environment. Therefore, a simple and reliable robot that can adapt to two environments with seven sets of structures is urgently needed. Based on the undulation motion principle of ray's pectoral fin, the undulation mechanism driven by 6 groups of crank rocker mechanism on both sides is designed, and the rocker mechanism is connected by rubber material to form the fin driven by rocker. The structure modeling and kinematics simulation of the robot are carried out, and it is confirmed that the mechanism of the ray can move effectively and the fin can realize regular fluctuation, which verifies the feasibility of the bionic ray underwater robot.