Abstract: The problem of target port/starboard ambiguity exists when the towed linear array is used as the bistatic active sonar receiving platform. The traditional method to solve this problem is to require the towing ship performing complex maneuvers, however, the real-time and continuous target tracking is difficult to guarantee. In this paper, the method using Doppler information to judge the of low speed targets on the port/starboard sides of a single linear array is studied. Conditions for the low-speed motion of the target are listed, and the relationships of Doppler information with sonar platform position and movement state are analyzed. Simulation and sea trial results show that the port/ starboard information of the target can be effectively discriminated by this method, which can be used as an auxiliary means in the bistatic active sonar.