Abstract: The Aircraft / Propulsion Integrated Assessment System is a computer aided assessment system developed for the conceptual and preliminary design phase of modern military aircraft. This system, for various missions and technical development levels, enables to evaluate a wide range of combinations of aircraft configuration and engine (turbojet or turbofan)or to obtain the optimal solution with the numerical algorithm for multiobjective optimization with constraints.A series of mission and aircraft / propulsion project, including the present aircraft modification and the future aircraft development, has been studied. During the optimization process, the best combinations of design parameters are selected. It is noted that the aircraft / propulsion system performance has been improved obviously.In addition, to use this system does not require considerable input and user experience. The output is easy to understand too. An aircraft / propulsion project analysis by the system requires less than 1 minute of CPU time(IBM4341)

Key words: aircraft / propulsion integrated design, assessment system, method and software