The invention belongs to the field of solid waste treatment, and discloses a preparation method of a high-volume fly ash-based water permeable brick, which comprises the following steps: (1) a step ofcarrying out alkali excitation on raw material fly ash and active industrial solid waste to prepare a geopolymer material, crushing the geopolymer material, and screening the crushed material to obtain granular fly ash as a coarse aggregate; (2) a step of compounding the coarse aggregate and a natural aggregate to obtain a water permeable brick aggregate; (3) a step of preparing the water permeable brick, namely a step of uniformly mixing raw materials including fly ash and the water permeable brick aggregate with a calcium-based activator, water and an alkaline activator to obtain a mixture,and then putting the mixture into a mold for compression molding to obtain a green brick; and then accelerating hydration reaction in the green brick by utilizing an autoclaved curing process, so asto prepare the high-volume fly ash-based water permeable brick. By improving the whole flow process of the preparation method, including the types of the adopted raw materials, the water permeable brick product with excellent mechanical properties can be prepared, and the dosage ratio of the fly ash is high.