The invention belongs to the field of aircraft structure design, and relates to a multi-coordinate system splicing composite material skin layer design method. According to the method, a wing skin composite material laying layer is divided into three coordinate systems, and the skin laying layer optimization is carried out by taking a wing symmetry axis as a boundary and taking a half-side wing. The optimized semi-side wing layer sequence scheme is mirrored by taking the skin symmetry axis as a mirror image to obtain a left and right side skin layer sequence. The engineering practicability isfully considered. The design difficulty is low. The design period is short, and the skin symmetry and the forming assembly effect are good. Compared with a first existing layering design method, the performance of composite fiber materials can be more effectively utilized. It is guaranteed that stress characteristics of skins on the two sides of the wing are consistent. Compared with a second existing layering design method, the integrity of the skin is guaranteed. The forming and assembling difficulty of the skin is greatly reduced, the structural weight is reduced, and the method can be applied to engineering practice.