In the field of NDT, infrared thermal imaging testing has an important place. In the use of infrared thermal imaging testing to detect defects in the process, by the processing technology and the influence of the surrounding environment, the surface roughness of the equipment to be detected are different, the emissivity of the surface of the material is not uniform, resulting in a large error in temperature acquisition. To address this problem, a global detection method for infrared thermography with correctable emissivity is explored in conjunction with the fundamental law of thermal radiation. The intention is to correct the surface emissivity of the material and to reduce the risk of safety issues such as misdetection and omission of defects that may occur during the inspection process. The simulation and experimental results show that: on the one hand, when using infrared thermography detection, the surface roughness is different and it will seriously interfere with the accuracy of the detection, the larger the roughness, the higher the detected radiation temperature; on the other hand, the use of the separation of temperature method can be achieved by correcting the surface of the object, which results from the roughness of the different emissivity that brought about by the different impact of the different simulation, experimental results show that the corrective accuracy of up to 70% or so, and can reach a maximum of more than 75%. Based on this corrective detection method, it can effectively achieve global detection based on infrared thermal imaging technology, reduce the impact of the emissivity on the detection accuracy of infrared thermal camera, improve the detection accuracy, and greatly improve the efficiency of defect detection.