Polarization is a crucial dimension in the light field, alongside intensity and spectrum, and holds significant promise in applications such as target recognition, military reconnaissance, and infrared target detection. Artificial objects, such as spacecraft engines and high-speed aircraft, typically reach temperatures of several hundred degrees Celsius, exhibiting high-temperature self radiation characteristics. However, there has been relatively little research on the infrared polarization characteristics of targets at high temperatures, particularly concerning the polarization properties of different metal surfaces under elevated temperatures. To investigate the polarization characteristics of high-temperature metal surfaces, a bidirectional reflection distribution function model based on microplane theory was systematically developed. This model incorporates both specular and diffuse reflection characteristics, establishing a mathematical framework for the BRDF of metal spontaneous radiation energy and the degree of polarization of infrared radiation. Through derivation and calculation, the influence of various surface roughness and temperature conditions on the polarization degree of infrared radiation from metals was analyzed. Simulation results indicate that at the same temperature, higher surface roughness of the metal leads to a lower polarization degree. Conversely, under the same roughness, the polarization degree increases with rising temperature. In parallel, thermal imaging of spontaneous radiation polarization was performed using an LGC6122 long-wave infrared camera and a WP25M-IRC infrared gate polarizer. The targets studied were iron and 45 steel, within the 8~14 μm wavelength range, at temperatures of 150, 200, 250, 300, 400, and 500 ℃. Experimental observations revealed that, influenced by Planck's blackbody radiation law, the surface temperature of the metal is positively correlated with its spectral integral polarization degree: as the temperature increases, so does the spectral integral polarization degree. Additionally, the polarization degree gradually increases with the observation angle, peaking within the 70°to 80° range. The findings of this study aim to enhance the accuracy and reliability of thermal imaging and optical sensing technologies in infrared target detection and otherrelated applications. Furthermore, they provide a reference for further exploration of infrared detection technologies in complex environments.