Aiming at targets performing uniform linear motion, the target course is obtained with intial target course angle calculated by using three azimuths at any different time, according to the relative motion model in torpedo attacking theory. Based on the simple linear regression and bearing sequence, an accurate estimation algorithm of target course is proposed. The influences of the time period of observed data and course accuracy on estimation results are analyzed. The simulation results show that the proposed algorithm is of high accuracy, which is also practicable while the measuring error is relatively large. Moreover, the target course estimation result has the advantage of high accuracy and stablity with the increasing of observed data length, the change rate of azimuth, and the precision of azimuth.