将多孔介质内孔抽象为分形曲线,并以该曲线的维数作为多孔介质的结构参数—谱维数d,藉此建立了气体在介质内的扩散通量计算式,并给出了测量分形结构码尺的计算方程和多孔介质谱维数的测定方法.由双组分气体在Ni/r- Al_2O_3催化剂上的扩散实验数据,计算出该催化剂的谱维数d=1.10. The internal pore of porous media is abstracted as a fractal curve, and the dimension of the curve is taken as the structural parameter of the porous media - the spectral dimension d, so as to establish the diffusion flux equation of the gas in the medium, The calculation equation of the structure yardstick and the determination method of the spectrum dimension of the porous medium were calculated.The diffusion spectrum of the catalyst on the Ni / r-Al 2 O 3 catalyst was calculated by the experimental data of the two component gas d = 1.10.