To obtain the information of dynamic attack zone in real time online among engagements of flight vehicles, a new concept, dynamic attack zone of air-to-air missile after being launched, was proposed, and the definition of the new concept was presented. Based on the mathematic model of an air-to-air missile which includes all sub-system models such as aerodynamic, engine, 3-D proportional navigation guidance law and so on, some typical cases of dynamic attack zones of air-to-air missile after being launched were numerically simulated by very fast simulation algorithm (VFSA). The numerical simulation results show that the fight envelope of dynamic attack zone of air-to-air missile after being launched is different from traditional dynamic attack zone, and dynamic attack zone of air-to-air missile after being launched is not always inside traditional dynamic attack zone.