Abstract: Based on the study and analysis of the undeformed /deformed coal samples from No.8 Mine of Pingdingshan and No.6 Mine of Hebi by diffusion experiment, combined with the new model of the dynamic diffusion coefficient and using experimental data, the initial diffusion coefficients (D₀) under three adsorption equilibrium pressure (0.5 MPa, 1.0 MPa, 1.5 MPa) were calculated respectively, the influence of different coal structures, different metamorphic grades, different particle sizes on D₀ of coal samples under different adsorption equilibrium pressure is discussed preliminarily: on the whole, the initial diffusion coefficient D₀ of deformed coal is higher than that of undeformed coal; the initial diffusion coefficient of meager lean coal from Hebi is less than that of fat coal from Pingdingshan; with the change of pressure, for the deformed coal, the initial diffusion coefficient of coal sample with the size of 0.5 mm to 1.0 mm is obviously higher than that of 0.25 mm to 0.5 mm; there is similar rule to follow of two kinds of D₀ with different particle sizes for the undeformed coal.