Abstract: In order to study the degree of discrepancy for 1.06 μm/3.5 μm/10.6 μm threewavelength laser attenuation due to the missile tail smoke, we established the opening smoke channel test platform. The shrink ratio engines filled up by 3 different kinds of propellant were planted at the head of the smoke channel, and the plume were formed while engines worked. The multiwavelength laser emitter and receiver were placed by the side of smoke channel along the diameter direction, so as to obtain the multiwavelength laser transmittance . The results show that the laser attenuation effected by smoke was related to the particle radius of smoke, and in the 400 m smoke channel environment, the maxim transmittance of 10.6 μm laser is 104 higher than that of 1.06 μm laser. These results are benefit to the improvement and upgrading of laser guiding weapon system.