In order to improve the mobility and flexibility, a six-degree-of-freedom bionic robot dolphin with image transmission function is designed. A 4-joint system consisting of a rigid head, a yawing waist and a 2-joint pitching tail of the robot dolphin is designed. Arduino Uno3 MCU is used to output PWM signals to control 7 steering engines, the electrical system control scheme and waterproof sealing scheme are formulated, PS2 handle is used to remotely control the robot dolphin, the tail joint swings up and down to achieve propulsion, the waist yaw joint turns, and the steering engine drives the counterweight block and a pair of single-degree-of-freedom pectoral fins to achieve pitch attitude adjustment. The feasibility of the scheme is verified by experiments. The results show that the robot dolphin achieves the motion postures of acceleration and deceleration, yaw, pitch, turning in place and double pectoral fins beating water.