The invention discloses a method for preparing a waste-based geopolymer material, and belongs to the technical field of waste comprehensive utilization and building material preparation. Building waste dust is adopted as a raw material and is blended with pulverized fuel ash and broken glass powder after high-temperature calcined activation, water glass prepared through dissolving and boiling with rice hull ash is adopted as an alkali activator, slurry with good liquidity is prepared and poured into a mold, cold press molding is carried out, and the waste-based geopolymer material is prepared under the hydrothermal condition of continuous mechanical external force action. The prepared finished product is high in durability and corrosion resistance and long in service life; compared with the traditional process, the reaction efficiency of geopolymer is improved, the generation period is shortened, the preparation process is low in carbon and environmentally friendly, and secondary utilization of waste is achieved.