Abstract: During the mining process of Jinggong Coal Mine, there is an objective goaf space, and accurately grasping changes in the elevation of the floor of the goaf is a prerequisite and necessary conditions for the rational utilization of the goaf.We take the goaf area in the southern part of the third mining area of Sangshuping No.2 well as the research background.Based on 13 geological boreholes near the southern part of the third mining area, the Kriging interpolation algorithm is used to interpolate the elevation of the coal seam floor in the southern part of the third mining area.The elevation of the goaf floor at each location in the southern part of the third mining area with an adjacent spacing of 5m is obtained.Using the surf function in Matlab software, a three-dimensional geological model of the goaf area in the southern part of the third mining area is constructed.The location for sewage purification and injection in the southern goaf of Sangshuping Well No.2 was determined to be at the central water tank on the eastern boundary of the southern area of the third mining area.The outlet position was determined to be at the coordinates of the northern boundary of the southern area of the third mining area（19 459 840,3 959 570）,with an elevation of 255.622 m for the outlet borehole.The water accumulation range in the goaf was 360 425 m²,and the water accumulation in the goaf was 48 862.94 m³.