Abstract: This paper proposes a novel backward-swimming method of biomimetic carangiform robot fish based on its body and tail undulation. The motion law of the carangiform robot fish is modified according to the backward-swimming law of European eel to achieve the backward-swimming motion of the robot fish. A qualitative kinematic analysis of the robot fish swimming in water is given to analyze the propulsion produced by the undulation of the multi-link tail and the backward-swimming method. Combining with other motions, the approach of the turning in backward-swimming and the emergency stop are given. Experimental results of the robot fish's motion are given and the performance is analyzed.