The invention relates to a coal gangue-fly ash-sludge substrate and a mycorrhiza technology for restoring ecology of a mining area. The invention belongs to the technical field of environmental protection, and relates to an ecology restoring technology, in particular to a method for restoring the ecology of an abandoned coal mine area. The method for restoring the abandoned coal mine area by the mycorrhiza technology of the invention adopts a composite substrate prepared by mixing fly ash, coal gangue and sludge, and comprises the following steps: a, preparing an inoculant; b, preparing a basic plant material; c, carrying out inoculating mycorrhiza treatment on the plant by the inoculant obtained in the step a; d, analyzing the physicochemical property of the abandoned coal mine area, and carrying out mixed treatment to form the composite substrate; and e, sowing seeds on the composite substrate surface layer of the treated abandoned coal mine area. The method of the invention can improve the adaptability of plants to the complex adverse environment of the abandoned coal mine area, wherein the adaptability comprises stronger nutrient acquisition capability and cold resistance, thereby fully utilizing waste and sludge in the mining area, and solving the source problem of other soil for melioration in the mining area.