In order to improve the swimming efficiency of the robot fish in the propulsion mode, a 3-joint bionic robot fish platform was designed with shark as the bionic object. According to the swimming mechanism of the carangidae, the large-torque steering gear is used to simulate the swing of the shark. The CPG control algorithm is used to realize the movement, turning and other movements of the robot fish in different speed positions. The directional cruise of the robot fish is realized by the PID algorithm. Carry out test on robot fish prototype. The test results show that the design can provide reference for the design of the 3-joint bionic robot fish.