Due to the particular work environment of the robotic fish, it is difficult for them to communicate with others underwater. In this paper, an underwater electric current communication system which is integrated into the bionic robotic fish is developed firstly. It is worth noting that it solves the problem that several underwater robots can't communicate with others in short distance by the way of traditional communication. Secondly, series of experiments are designed to verify the feasibility of the theories aiming at the physical characteristics of the current field, and the bit error rate (BER) is adopted to evaluate the stability of the communication system. Finally, the underwater electric current communication system is successfully used to control the different swimming modal through the external transmitting device. This communication system has a broad application prospect in the short distance communication of underwater robots.