Polarization imaging contains rich target parameters including spectrum, radiant intensity, polarization state, space geometry, etc. Polarization imaging can improve the target detection and recognition ability. The infrared polarization imaging is a new infrared detect technology in recent years. Infrared polarization imaging mainly aims to detect and identify the target with the difference of infrared radiation polarization characteristic between target and scene. But the state of polarization is affected by transmission medium in the transmission process of infrared radiation polarization information while the common method is to analyze the infrared radiation polarization characteristics of target that is not able to describe effects of all interrelated parameters and is difficult to estimate influence factors in the process of transmission. The equation of infrared polarized radiation is established through bidirectional reflectance distribution function based on micro-facet theory. And the mathematical model of the relationship between infrared radiation polarization degree and emissivity is derived in this paper. Result shows that the influence of target surface emissivity on the infrared degree can be ignored. On the basis of theoretical analysis, the infrared spectrum polarization imaging tests are unfolded, and the analysis of test data is consistent with the theoretical analysis. It is concluded that the correlation between the polarization degree of infrared and the emissivity of target surface can be neglected. The research production of this paper is conductive to increase of target detect efficiency, and it will provide new ways and means for camouflage target detect and identify. Therefore, the research production can be applied to detect and identify the camouflage target that is accomplished camouflage through change emissivity of camouflage target surface.