Abstract: There is a huge amount of coal under buildings in China, and the current mining methods cannot safely and efficiently extract coal resources under buildings, making a large amount of coal resources unable to be effectively recovered. In order to liberate the coal resources under the building and extend the service life of the mine, based on the mining conditions of the Mahuangliang coal mine, a four-stage strip paste backfill mining technology under the building was proposed, and reasonable process parameters were determined. Taking the disposal of solid waste of coal gangue as the starting point, a gangue paste backfill material is prepared and its performance is analyzed. The four-stage paste backfill process is described, and the backfill strip plugging and high-efficiency roof connection process are designed. Combined with the field application, the effect and economic benefit of four-stage strip paste backfill mining are analyzed. The research and practice show that the flow and mechanical properties of gangue paste backfill material meet the backfill requirements of Mahuangliang coal mine. After mining with four-stage paste backfill mining technology, the roof connection rate of backfill body is more than 98%, and the maximum deformation value of surface building deformation and movement is within the fortification index, which realizes the successful practice of backfill coal mining under coal mine buildings. This mining method can liberate the coal resources under the building of about 10Mt in Mahuangliang Coal Mine, extend the service life of the mine, jointly dispose of coal gangue, and avoid the impact of gangue stacking on the ecological environment. It has good economic and social benefits. The research provides a useful reference for the "three under" mining of Yuyang District and surrounding mines.