Distinguishing the target accurately is the basis for the Anti-Ship Missiles (ASMs) to select the scheduled target in a ship formation.Firstly,under the necessary conditions for radar homing head to capture a target in a formation,the models of range difference and angular difference between the target and non-target are established based respectively on given homing distance and given attack angle.Then,with consideration of the influence of target maneuvering tactic and missile firing error,the models of range difference and angular difference are established on the condition that the homing distance and attack angle are uncertain.Finally,simulation analysis is carried out after setting a scenario.The results show that the attack angle restricts each other with the homing distance on the condition that the target is distinguished accurately.In other words,the homing distance should be selected reasonably according to different attack angles.