The invention provides a coal-ash-based ozone oxidation catalyst and a preparation method and application thereof. According to the coal-ash-based ozone oxidation catalyst, coal ash serve as a carrier, and transition metal or transition metal oxide or salt serves as an active component, wherein the mass ratio of the coal ash to the transition metal is (5-20): 1; the transition metal is selected from one or more of cobalt, titanium, copper, iron, manganese, zinc and nickel. According to the ozone oxidation catalyst, the coal ash serves as the carrier, solid waste resources can be recycled, and materials are low in cost and wide in source; the catalyst is high in catalytic activity, great in water quality fluctuation resistance and capable of effectively degrading high concentrated organic wastewater, the COD removal rate reaches 70-90%, biodegradability (BOD/COD) of waste water is raised to 0.50-0.80, the application scope is wide, and the coal-ash-based ozone oxidation catalyst and the preparation method and application thereof are applicable to biochemical pretreatment and deep treatment of multiple types of waste water.