Abstract: Epoxy resin paint(EP) and polyurethane paint(PU) were removed from 2024 aluminum alloy surface by nanosecond pulsed fiber laser. Different laser power, scanning speed and pulse frequency were set, and the research on laser paint removal technology was deeply carried out. The single factor influence rule of different laser parameters was characterized by the evaluation indexes such as surface paint residue and ablation rate, and the laser power density curve was selected to explore the process threshold. The results show that the power density of different paint layers/substrate systems that completely remove paint without damaging the substrate is between the threshold T3(complete paint removal threshold) and T4(basal damage threshold). The competition among laser absorption coefficient, ablation pit defects and the binding force of paint layer/substrate leads to the difficulty of removing paint as white paint<green paint<yellow paint, PU<EP. The Sa(removed paint surface roughness) and PVH(peak valley height difference) of the substrate surface after complete removal of paint are different from the original surface in micron scale, which can ensure the quality of the repainting process and the amount of paint material. The microhardness and residual stress increase due to the plastic deformation, crystal structure change and surface hardening of the substrate, and the mechanical properties of the material are improved.