The traditional methods for Missile Attack Envelop (MAE) calculation have poor pertinence and real-time performance, which are difficult to provide a basis for decision-making in rapidly changing situations.A new method of air combat tactical decision-making is proposed combining offline computing with online computing of MAE.The offline computing analyzes the influence of the enemy aircraft and our aircraft to the MAE, based on which the geometry model is established.The online computing assesses the combat situation quickly and quantitatively by considering the relative attitude information of both sides and the offline MAE model, and generates air combat tactics.The synthesized experimental results show that, the generated tactics significantly improves the operational efficiency, and outperforms the traditional tactics based on the front missile launching principle against targets.