Abstract: Target detection in smoke environment using laser active imaging is of great significance. Suppressing scattering effect of light effectively is the key to improve the imaging quality. According to the polarization theory of light, the polarization characteristics of a single-scattering photon changing with the scattering angle is analyzed, and the polarization characteristics of light transmitting in the smoke environment is simulated. The polarization difference method is proposed to suppress scattering light and an imaging experiment is set up at last. It is shown that when light is transmitting in smoke, the scattering light is mainly made up of small-angle scattering light, which still retains the initial polarization characteristics of the incident light. Compared with the direct imaging method, the polarization difference method can effectively filter out the influence of small-angle scattering light and enhance the detailed information of imaging target and the image contrast.