Using the T-matrix method, detailed numerical computation and comparative analysis on the distributions of light scattering matrix of fire smoke particles and non-fire smoke particles are carried out. The results show that when the wavelength of incident light changes, the degrees of variation on elements of fire smoke particles are different from those of non-fire smoke particles. By using dual-wavelength pulsed laser as incident ligh, through detecting appropriate element of light scattering matrix and combining XOR logical operation, the fire smoke particles can be distinguished from non-fire smoke particles, thereby reducing the misinformation caused by non-fire smoke particles.