In addressing the formidable challenges posed by the mining of a gently inclined thin ore body of a fluorite mine in Guizhou, which includes arduous mining conditions, low mechanization levels, and constrained resource utilization, combined with the unique occurrence characteristics and mining technical conditions of the ore body, the mechanized upward horizontal layered filling method was proposed, this study introduced its stope structural parameters and extraction technology, a comprehensive analysis of the stope stability was conducted, utilizing the Mathews stability graph method and advanced numerical simulation software, and the results show that the stope span, the exposed area of the hanging wall and the roof are less than the theoretical limit, the settlement of the stope roof is between 0.96m~4.32mm, the maximum arch of the bottom is 3.5mm, the maximum compressive stress is 9.8MPa, the tensile stress value is far less than the tensile strength of the filling body, which stands at 0.44MPa, and the plastic zone does not form penetration. The application results of site test show that the stope production capacity is 150t/d, the stripping ratio is 12.96m/kt, the loss rate is 10%, and the dilution rate is 8%, the significant economic benefits have been achieved.