Abstract: By analyzing the detection principle of active infrared thermal imaging method and its application abroad, the applicability of infrared thermal imaging method to coating quality detection is determined. Aiming at the delamination defect of arc spraying coating and substrate, an infrared thermal imaging detection of coating quality is carried out. The test results show that the active infrared thermal imaging method can realize accurate, rapid and non-contact detection of the delamination defect in the coating, and the delamination degree can be effectively distinguished by using the thermal diffusion curve.