The invention discloses a preparation method of a high-performance gas-filling building block composite material, belonging to the technical field of building materials. According to the invention, the coal ash, tailings, slag, yellow sand and the like are used as major raw materials, the cement, carbide slag and lime are used as excitants, the aluminum powder paste and hydrogen peroxide are used as gas production agents, the phosphoric acid and water glass are used as foam stabilizers, the ardealite and titanium gypsum are used as retarders, and the calcium lignosulphonate and hydroxylmethylcellulose are used as dispersing agents. The preparation method is characterized in that the coal ash, the tailings, the slag, the yellow sand and the like are subjected to the technologies of PLC system grinding, mixing, pouring, precuring, cutting, steaming and pressing, building block separation, packing and the like; and the technology for preparing the silicate composite material for a building is adopted. Through the invention, the produced building block has the characteristics of stable chemical property, excellent physical performance and the like. The preparation method has a simple technology and high efficiency, can consume a great quantity of solid wastes, prevents the emission of three wastes and the environmental pollution, reduces the environmental pollution caused by other wastes, and creates obvious economic and social benefits.