In response to the problem of collapse pit treatment in underground metal mines and open-pit to underground mining processes, taking Miaogou Iron Mine as the engineering background, the permeability characteristics of overlying cemented filling layer under the influence of loose particle size, slurry concentration, and ash sand ratio were studied through experimental methods. The results showed that for the same filling slurry, the larger the particle size of the dispersed particles, the faster the slurry penetration rate, the deeper the penetration depth, and the greater the impact on the penetration range; Under certain conditions of loose material properties, the slurry concentration is one of the main factors affecting the fluidity and permeability of the slurry. Intermittent filling and grouting can be adopted to increase the slurry concentration and reduce the infiltration depth of the filling slurry; When the gray sand ratio is large, the block size formed by the collapse of the filling layer is relatively large, which is conducive to reducing ore impoverishment. It is recommended that the range of the gray sand ratio of the filling slurry be 1:12~1:16. The research results can provide parameter guidance and reference for the treatment of tailings filling in surface subsidence pits under similar conditions in mines.