The mathematical model of the relationship between infrared polarization angle and other parameters such as surface refractive index, reflectivity, and the detection angle was derived, based on the equation of infrared polarized radiation through micro-facet theory. Reasonable simplification for the model was made in simulation. The curve show that the polarization angle changes with the incident angle monotonously, in agree with the experimental results. It is concluded that the correlation between the polarization angle characteristics of the target edge contour and the detection wavelength can be neglected. It is difficult to distinguish between target and background by spectral radiance contrast when they have small radiation difference. While the target edge features can be obtained from the polarization angle contrast. A new method to calculate target gesture information was proposed based on geometry features of the target and the relative detection position.