Abstract: Based on the analysis of two intercept trajectories of anti-torpedo torpedo(ATT), mathematical models of converse trajectory and direct trajectory were established. The relationship between the azimuth of incoming torpedo and the launching angle of ATT was discussed. The influence of ship′s course and distance measurement error of incoming torpedo on the intercept probability of ATT was simulated and calculated by Monte-Carlo method. The relation between the intercept trajectory and the performance of ATT was also discussed. Simulation results indicate that converse trajectory has a higher intercept probability. Accurate positioning of the incoming torpedo can effectively improve the intercept probability of ATT. And increasing homing detection distance and search sector angle can also enhance the intercept probability of ATT.