Polyurethane-based black paint is a kind of gloss and flat paint used for stray light shielding in optical imaging systems. Experiments of infrared laser irradiation effect on polyurethane-based black paint are carried out in a vacuum cryostat. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) are used to investigate the changes of the surface morphology, chemical composition and structure. The mechanism of interaction between laser and polyurethane-based black paint is studied. Based on macro phenomenon and micro-appearance analysis, the degree of damage is proposed. The experimental data and results of simultaneously differential scanning calorimetry-thermogravimetry (SDT) analysis indicate that damage is mainly caused by laser heating; the deposition of heat generated by laser changes color of the coating and leads to pyrogenation, carbonization and thermal ablation. The morphologies obtained from SEM show that surface of the coating is covered by many nondirectional fine cracks and the pigment particles agglomerate together after laser irradiation. XPS analysis for the surface of coating with and without laser irradiation reveals that laser irradiation changes the chemical composition and structure of the coating, and the C-N bonds and O-C＝O double bonds of binder are more easily cut off and destroyed.