Due to its light weight, high strength and durability, Al7075-T651 alloy is widely used in the manufacture of aircraft fuselage structures, such as aircraft shells and protection plates. However, parts such as aircraft shells and casings are relatively thin and difficult to process, so the process parameters for processing aircraft parts must be strictly selected and controlled. The milling force during the milling process is one of the important indicators affecting the quality of processed alloys. As a consequence, it is necessary to conduct further research on the milling force during the milling process. In this paper, the alloy workpiece is simulated based on ABAQUS, and the milling process under different parameters is simulated to analyze the influence degree of the parameters. Finally, a mathematical model was established between milling parameters and milling forces, and its fitting degree was further verified. This paper provides some theoretical basis for selecting machining parameters.