Based on equivalent particulate model and fractal theory，using the Mie theory and discrete-dipole approximation，the scattering by aggregated soot particles of the 06328?μm incident wave is computed. Then based on radiation transportation theory，and numerically calculating the transfer-characteristics of electromagnetic wave propagating in soot by using Monte Carlo method，the author gets the relationships of the reflectivity and transmissivity of soot with the changing incident angles，soot thickness and density，and analyses these factors affecting the reflectivity and transmissivity. This provides an efficient approach to the research of transfer-characteristics of electromagnetic wave in poly-disperse highly dense media.