Abstract: In order to analyze the influence of porosity of porous media on the effectiveness of grouting in loose layers, indoor experiments are conducted to study the permeability and diffusion range of slurry in porous media under different porosities. Experimental studies have shown that the diffusion radius of slurry in porous media is related to its porosity. When the porosity of the porous media is below 25%, the diffusion radius of slurry will rapidly decrease; when the porosity of the porous medium exceeds 25%, the diffusion radius of the slurry slowly increases; grouting reconstruction can significantly improve the anti-seepage ability of porous media. The closer the injection hole is, the smaller the permeability coefficient of the injected medium, the stronger the anti-seepage ability, and the highest anti-seepage ability can be increased by about 99%; when grouting and reconstruction porous media in an anhydrous environment, the shape of the stone body is mostly a circular cone, with a narrow diffusion radius of the slurry. This research achievement can provide theoretical support for the anti-seepage reconstruction of loose layer grouting.