This invention discloses a method for preparing a catalyst for catalyzing the degradation of organic pollutants in printing and dyeing wastewater by ozone, wherein the catalyst comprises a porous carbon material as a substrate and metal oxide nanoparticles deposited on the surface of the substrate. The method comprises the steps of: allowing a mixture of resorcinol, formaldehyde, trimethylhexadecyl ammonium bromide, multi-walled carbon nanotubes and deionized water to react to form cured product, which is then calcinated and carbonized at high temperature to produce the porous carbon material; impregnating the resulting porous carbon material with nitrate solution, drying the porous carbon material, and calcinating it at high temperature, wherein the absorbed nitrate is decomposed into metal oxide and embedded into the porous carbon material. Depending on the requirement of applications, the raw material for preparation of the catalyst of the present invention can be pulverized to screen out the appropriate particle size to fit into practical engineering applications. With the optimization of catalytic oxidation process, the catalyst can be used to promote the rapid degradation of organic matter in printing and dyeing wastewater by ozonation, and the percentage of degradation can be greatly improved. As a result, indicators of wastewater, including the chromaticity and COD, can be significantly reduced.