Advanced composite materials are widely used in modern aircraft due to their small specific gravity

high strength and good fatigue performance. The deformation and thickness control of composite parts during thermoforming is difficult

and the rationality of component positioning and tolerance distribution greatly affects the quality and efficiency of aircraft component assembly. In this paper

a composite material shield assembly is taken as an example to study the effect of two different CNC milling edge positioning schemes on the tolerance distribution in the whole assembly process

and use MATLAB software to calculate and simulate the simulation tolerance between each manufacturing tolerance and the final assembly tolerance. The mathematical relationship provides a basis for the positioning of the CNC milling edge and the design of the frame.