Abstract: To the combat aircraft operational effectiveness evaluation, mission effectiveness concept was presented based on combat aircraft’s different missions. With the probability analysis method, aircraft operation procedures were studied and abstracted into a group of probability values, and relevant evaluation models were built for several different typical operation procedures. These models have much more matter-of-fact significance and will be very helpful for commanders to make much reasonable and scientific mission plans and thus make much better use of combat aircraft and weapons available to implement certain mission. The new models are simple, easy understanding and conducting, their computing resources and time are more acceptable than that of traditional emulation methods while giving reasonable results with calculation accuracy close to the former. Example results show that the models are available and believable when evaluating mission-based operational effectiveness of combat aircraft, which concerns different aircraft platform with different weapon striking different target in different combat scenario.