The effectiveness evaluation of airborne fire system is a vital part of airplane-s effectiveness evaluation on combat. A modeling method that combined the theories of influence diagrams and Lanchester equation was applied to build the air-combat model of airborne fire control systems. The damaging ratio of air-combat for different airborne fire control systems, which reflected fire control system-s influence on air-combat dominance, was computed. The curves were drew about how the performance index of fire control systems (targeting error, identifying probability, and attacking time) affected air-combat damage ratio. This method provides credible basis on how to improve the arming of airplane-s fire control system. This model lays a foundation on evaluating airplane-s air-combat effectiveness and makes some sense on commanding practical combat.