The low permeability sandstone reservoir has poor development effect and serious gas channeling in the block W of Zhongyuan oilfield ,Sinopec. In order to investigate the influence of rock surface roughness, pore distribution uniformity and homogeneity on porous media of the reservoir. Based on the theory of petro physics, fractal and seepage mechanics, laboratory experiments were carried out. box dimensions of porous media were calculated by Frac Lab and Frac Lac software respectively, based on Gaussian distribution, Fourier analysis, power law and least square regression. The results show that the porous media of block W reservoir is of fractal characteristics, fractal dimension is about 2.58, coarse porous media surface, complex pore structure, more micro pores, serious irregular heterogeneity and high flow resistance. The fractal dimensions obtained by Frac Lab and Frac Lac software have good consistency. This research provides strong basic support for enhancing oil recovery, oil and gas seepage law and porous transport properties, in a low permeability sandstone reservoir has excellent practical significance.