On the basis of advantages of Long Wave Infrared (LWIR) polarization imaging in the field of target detection and recognition, a LWIR polarization imaging detection system is built. The LWIR polarization images of some typical indoor and outdoor objects are collected by the system. The image information of three kinds of targets, such as Stokes vectors ($I, Q, U$), degree of linear polarization, angle of polarization and two combined features δ and ρ, is extracted. Their characteristics are analyzed in detail. A new method for enhancing target-background contrast based on the infrared polarization information obtained is proposed. The experimental result shows that the method is feasible and effective.