The computing method of S / N under the active blanket jamming and passive jamming conditions is presented. The computation model of the single - shot kill probability of antiaircraft missile under the electronic jamming condition is built. The concept of anti-jamming improvement factor is introduced. The effectual jamming probability of deception jamming and the target detecting probability under the electronic jamming condition are analyzed. Finally, the computation model of the single continuous fire kill probability of antiaircraft missile under electronic countermeasure conditions is given.