First of all, the technological framework of the model for calculating the kill probability of multiple shots is established, followed by the corresponding calculation equations relating to two cases of both shooting errors and shooting index. For getting rid of the difficulties facing the calculation of kill probability of multiple shots, an approximate treating mode converting general shooting errors model into two-type errors model was adopted in the establishment of approximate equations used in mean point of impact method and average correlative coefficient method. The calculation equation for kill probability of multiple shots related to index was the first one established in that field, which has solved the difficult problem of calculating kill probability of multiple shots in the simulation and evaluation field of shooting efficiency of weapon systems.