Abstract: Different from the traditional “water damage” problem, Yuxi Dahongshan Mining Company adopts the point-pillar upward horizontal slicing and filling method for deep mining of No. I copper mine belt. Due to the poor drainage effect after hydraulic filling in a large range of goaf, the backfill body contains a lot of filling water, which has been continuously replenishment and downward penetration in the production process for many years, forming a water filling body. It poses a serious threat to the safety of mining up in the lower and middle parts. The research has carried out in-depth research from the characteristics of water filling body, water exploration and drainage scheme, isolation top pillar remaining thickness and safety mining technology. The characteristics of water charging are obtained by means of theoretical calculation, drilling and geophysical exploration. A water exploration and drainage scheme is formulated to drain water from the upper middle filling body by constructing drainage holes upward from each stoping link. By means of theoretical calculation and numerical simulation, the minimum safety thickness of isolation top pillar in each middle section is obtained under the conditions of dewatering and water charging. The safety technology of stoping and the scheme of filling and reducing drainage are optimized. The results of the project have been successfully applied, and the resources have been recovered to the greatest extent while ensuring the safety of mining, which has a high reference significance for mines that have similar “water damage” problems.