Abstract: In order to improve the measurement efficiency of coal mine dust distribution and shorten online measure time, based on light scattering theory, using the good approximation performance of eikonal approximation method on scattering wave, an improved eikonal approximation equation is established to calculate complex particles extinction coefficient problem with Mie theory of total light scattering. The common unimodal R - R narrowband and broadband particle size distribution is carried out experiment simulation. The results show that reconstruction model meets scheduled distribution, to set 5% random noise to the simulation parameters, the particle size distribution reconstruction can get satisfactory results; extinction coefficient matrix is improved 48 times.