Abstract: Anti-interference of cloud and smoke is a hard problem for laser fuse. In this paper, a technology of polarization dection was presented based on the polarization degree difference in reflection of artificial entity targets and backscattering of smoke. The backscattering signal received by laser fuse was redused selectively as the extinction effect on smoke backscattering signal was much larger than the target reflection signal. The detection probability calculated theoreticaly has been reduced to 0.4% of the original detection system by using the principle of threshold detection and detection probability curve. Finally, analysis shows that the system was expected to be a new anti-interference method since it can not only detect the target but also reduce the detection probability of the smoke significantly according to the experience in engineering development.