Traditional thermal emission polarization model ignores the microscopic distribution, and taking this into consideration to expand modeling and simulation research of infrared thermal emission polarization characteristics. Model of the degree of polarization of the infrared thermal emission is built based on the microfacet polarized Bidirectional Reflectance Distribution Function (pBRDF) and the microstructure distribution. Utilizing the difference between the parallel and perpendicular components of the emissivity of the infrared thermal emission divided by the sum of them represent the degree of polarization. And the relationship between emissivity and hemispherical reflectance is obtained according to the Kirchhoff's law and the microfacet BRDF. Polarizing the microfacet BRDF to calculate the directional hemispherical reflectance and then directional emissivity matrix, and last to get the degree of polarization. The simulation results show that the curves of the relationship between the polarization and the emission angle of the infrared thermal emission are consistent with the actual measurement results, and compared with the simulation results of traditional thermal emission polarization model, is closer to the measured value, especially in the case of the surface roughness is larger, can more accurately reflect the infrared thermal emission polarization characteristics.