Abstract: The system of polarized thermal imaging is more suitable to anti-camouflage than the classic thermal imager. If a polarizer inserts in front of a thermal imaging system, the system's operating range will be changed which had mainly studied in the paper in detail. Firstly, the NETD, MRTD and operating range of a polarized thermal imaging system were modeled from first principles of infrared physics. Secondly, the coefficient of the operating range gain of the polarized system compared with that unpolarized one was deduced. Lastly, the polarization and radiation contrast between a camouflage tank and grass and the operation range gain of the polarized thermal imaging system were calculated and analyzed. The results show that the polarization contrast is much larger than the radiation contrast. And the operating range of the polarized thermal imaging system is also larger than that of the unpolarized one when detecting a camouflage tank, which reveals the polarized one's better performance.