Base on Mie theory, reported the extinction coefficient of the aerosol and the detection range of image system during haze-fog episodes from visible to long wave infrared. The results show that during haze-fog episodes, the extinction coefficient will decrease and the detection range will increase , with the increase of wavelength. And a serial of image experiment with different wavelengths of visible and infrared image system have been performed to demonstrate the above conclusion. Shows that during haze-fog episodes the performance of infrared image system is better than that of visible image system, can solve the problem of visibility dropped sharply.