As a leading edge component, the aircraft fuselage skin can suffer severe damage to its surface coating structure due to the impact erosion of raindrops when the aircraft traverses through rainy conditions. With the increasing flight speed of aircraft, stricter requirements have been put forward for the rain erosion resistance of the fuselage coating. To clarify the mechanisms and affecting factors of rain erosion damage on the leading edge skin coating of aircraft and identify the damage criteria for rain erosion impacts, a single-jet impact test setup has been established based on a first-order light gas gun platform. With T300 carbon fiber composite material as the substrate, three different types and thicknesses of polyurethane coatings are applied to the surface. The effect of coating mechanical properties, impact velocity, angle, and other factors on the degree of rain erosion damage to the coatings is examined. A finite element model of the water jet impacting the composite coating structure during the impact process is developed based on Abaqus finite element simulation software to further reveal the rain erosion behavior and damage mechanisms of the coating material. The results indicate that when the high-speed jet impacts the coating, the simulated damage outcomes are generally consistent with the experimental results, showing uneven damage distribution at different impact angles, with deformation and delamination of the coating being the primary damage modes. This validates the rationality of the numerical simulation model method. The typical morphology of rain erosion damage is characterized by a circular damage area surrounding the central undamaged area. Under more severe impact conditions, the main damage modes are circular damage after peeling of topcoat and primer. It can be seen that cracks are generated due to the impact, and the edges of the cracks are lifted and broken, mainly in the erosion pit at the impact center, accompanied by the uplift of the surrounding surface layer, resulting in internal delamination damage. As impact conditions intensify, the surface coating cracks and peels off, resulting in circular detachment. The impact velocity and angle of the water jet are the primary factors affecting the degree of rain erosion damage to the coating. By combining simulation methods, the stress propagation patterns during the impact process are obtained. An increase in impact velocity directly leads to an increase in stress levels, causing surface coating detachment and internal crack delamination under stress during the impact instant, with the surface coating separating and lifting up. An increase in the impact angle reduces the velocity component in the vertical direction. In the horizontal direction, due to the presence of the impact angle, there is a significant difference in velocity between the lateral jet along the positive and negative directions of the impact projection, leading to differences in path stress levels in the simulation results and ultimately causing the damage morphology to exhibit a clear asymmetric distribution. Water hammer pressure and stress wave propagation are the main factors causing coating detachment and internal damage, while hydraulic infiltration and lateral jet effects are among the reasons for interlayer cracking in the composite skin coating structure.