Taking a certain type of propeller transport aircraft powered device flight test bed as the research object, a three\|dimensional flow field model is established by CFD method with numerical calculation and meshing. The previous flight test data and engine thermal cycle model output data are used as boundary condition computational. Numerical calculations of different Mach, flight altitudes and blade angle are carried out. The engine state being characterized by the blade angle, the influence of different altitudes, speeds and blade angles on the force of the inlet front cover and additional front body force are analyzed. The calculation results show that at different altitude, the resistance of the inlet might be changed with the blade angle and Mach. When state is at 0.5 Mach and height equalsto 6 km, the blade angle increases from 40 to 50, the nacelle front force decreases by 1 700 N, and the additional front drag decreases by 3 600 N. While the flight altitude has almost no effect on the additional front body force coefficient and the front cover force coefficient. The research provides data support for determining the external resistance characteristics of the turboprop engine in the subsequent flight test.