Abstract: The spatial evolution of the caving zone in coal mining areas and the assessment of the filling capacity of gangue slurry are the key issues that must be urgently addressed in the gangue slurry filling technology for goaf areas. To accurately calculate the filling space volume of the gangue slurry in caving zones and the amount of gangue to be disposed, this study took the No. 42208 working face of the Liangshuijing Coal Mine as the basic geological prototype, a numerical model of the mining−induced overburden damage was constructed by using the particle flow discrete element method. The development of fractures and the evolution law of void ratio in the mining−induced overburden were simulated and analyzed. The accuracy of the numerical simulation results was verified by comparing the measurement results. Based on the comprehensive theoretical analysis and numerical simulation results, the annual gangue disposal amount for adjacent filling of gangue slurry in goaf caving zones was determined. The results show that the average development height of the water−conducting fracture zone in the overburden of the No. 42208 working face of Liangshuijing Coal Mine is 67.00 m, with an average fracture−mining ratio of 19.14, the average development height of the caving zone is 20 m, with an average caving−mining ratio of 5.71. The development morphology of the water−conducting fracture zone in the overburden exhibits a regular trapezoidal feature. From the evolution of void ratio in mining−induced overburden, it can be found that the targeted area for gangue slurry filling in the goaf is mainly within 50 m horizontally form the coal pillars on both sides. within the caving zone on both sides of the goaf. The annual gangue disposal amount for gangue slurry filling in the goaf caving zone of the No. 42208 working face of Liangshuijing Coal Mine is approximately 330 000 tons. The research results can provide a theoretical basis for the efficient adjacent filling of gangue slurry in caving zones of coal mining areas, which promotes the green and low−carbon development of coal resources.