The invention discloses a plaster pumping filling material used for supporting mine enby left and a preparation method thereof. At first, natural anhydrite is grinded by an industrial globe mill, the fineness is controlled to be less than 1 percent in the weight of screen residue of 200 meshes, and the specific surface is between 4000 and 5000cm<2>/g; then 0.03 to 0.08 percent of air entraining agent, 0.5 to 1.0 percent of excitant, 1.5 to 2.5 percent of early strength admixture, 0.40 to 1.2 percent of accelerating agent as well as 0.5 to 1.0 percent of water reducing agent are mixed, and then uniformly mixed with 15 to 18 percent of natural anhydrite, 15 to 25 percent of cement, 18 to 25 percent of fly ash, 20 to 25 percent of stones as well as 20 to 25 percent of river sand in a batch mixer to obtain the plaster pumping filling material used for supporting mine enby left. The invention does not need calcining and grinding during production, and can save energies and reduce pollution; moreover, as the dosage of the water reducing agent is reduced, the production cost is reduced, and the market competition is improved, thus greatly promoting the technical development for future mine production; the production technique is simple; mechanical pumping is employed for construction; the invention is simple to be operated and brings more guarantee for the safe production of the mine.