In order to overcome the difficulty of analyzing warhead damage effect in ship-to-air missile flight test, a method of calculating warhead fragments damaging position of target is put forward. According to the property that dynamic scattering angle of rod warhead or focused fragment warhead is sole, the method calculates the dynamic scattering angle using optical identical frames measurement data of exterior trajectory, geometric parameters of target, etc, and then calculates the damaging position. Based on related mathematical models, the principle and steps of the method are given, and influences of relevant measurement factors to the calculating accuracy are analyzed by Monte-Carlo statistical simulation. The simulation results show that the accuracy is influenced seriously by the number and distinguish errors of identical frames, when two theodolites are distributed reasonably and the accuracy and sampling cycle of optical measurement are fixed. The conclusion is that the calculating method is validity and the accuracy can meet the need of damage analyzing.