Abstract: It is difficult to measure the flight thrust of Aeroengine directly.It is determined now by calculation with mathmatical relationships of the flight thrust to the physical quantities which can be measured directly.According to the definition and the expression of the thrust,as well as the conditions derived from them,a method of aeroengine thrust determination and its program are provided on the basis of engine part tests,model tests,engine ground test,altitude-simutation tests,and flight tests.At the same time,the important function of the altitude-simulation facility is also analyzed in respect of correct flight thrust determination.