Abstract: The aircraft skin structure is often subjected to low energy impacts such as hail and maintenance tools, resulting in damage to the fuselage structure and reduced aircraft performance. In order to improve the impact resistance of the skin structure, this paper established a low-speed impact finite element equivalent model of composite foam sandwich structure based on the Hashin failure criterion, and used ultrasonic C-scan to conduct nondestructive testing on the impact composite foam sandwich testing. The error between the simulation results and the nondestructive testing results was less than 10%, which proved the rationality of the impact equivalent model. Finally, the finite element equivalent model was used to optimize the design of composite foam sandwich skin structure of an electric aircraft fuselage. With the goal of improving the impact resistance, reducing the absorbed damage energy, and reducing the structural damage degree, the optimal composite foam sandwich structure ply design scheme was obtained under the same number of plies.