Abstract: Diffusion of ternary gas mixture of ethylene, argon and carbon dioxide in γ -Al 2O 3 was analyzed based on the network approach with the effective medium theory and smooth field approximation, and was verified by the Wicke-Kallenbach steady state diffusion experiment. The diffusion flux equation,including pore size distribution and pore structure parameter—mean coordination number,was calculated to get the diffusion properties of each substance without prior knowledge of the tortuosity of porous media from diffusion experiment. The alumina used in diffusion experiment had a larger range of pore radii from 1.0 to 1000.0 nm, which was cut into three intervals according to the three peaks on the diagram of mercury injection curve.The pore size and pore structure parameter could be obtained by sorption experiment. The diffusion experiment was carried out in an atmospheric cell,with temperature from 320～430 K. The results showed that the multi-component diffusion could be resolved with network analysis when pore structure (mean coordination number) and pore size (pore size distribution) parameters were known. After all, a useful method was established to describe the macro-properties of diffusion from the microstructure of porous media.