For the problem of jamming effectiveness evaluation of surface-type infrared decoy,the jamming effectiveness evaluation rule and model are constructed when surface-type infrared decoy defenses infrared image guided anti-ship missile. Using shielding interference as an example,the jamming success probability is evaluated by Matlab simulation when threatened situation,launching and maneuver decision scheme are given,then the tactical approach for improving the jamming success probability are obtained,and the tactical principle and method for surface-type infrared decoy defensing infrared imaging anti-ship missile are also formed.