In order to further study the effect of laser incidence angle on the surface cleaning of non-uniform coating, different inclined incidence angles of 90°, 75°, 60°, 45° and 30° were selected to carry out laser cleaning experiments on the non-uniform thickness of 6061 aluminum alloy. Surface morphology, roughness and hardness after treatment were measured, and a laser thermal effect model was constructed. The effect of laser on the surface temperature distribution and morphology of aluminum alloy matrix at different incidence angles was revealed by comparison between simulation and experimental results. The results show that, different incidence angles have significant effects on the removal of non-uniform paint layer and the damage degree of aluminum surface during laser cleaning. The surface roughness value of laser cleaning at 30° incidence angle is reduced by nearly 22 μm, or 80%, compared with the 90° vertical incidence laser. With the increase of the incidence angle, Vickers hardness after cleaning is gradually increased. The oblique incidence laser cleaning method has better effect on the treatment of uneven surface coating, and can significantly improve the surface smoothness. This study not only provides a valuable reference for the optimization of laser cleaning technology, but also contributes practical scientific data for the development of non-uniform coating surface treatment technology.