The invention discloses a water oxidation catalyst based on a porous carbon material and a preparation method thereof. The catalyst is composed of a porous carbon skeleton and metal hydroxide, wherein metal hydroxide particles are uniformly distributed and defined in holes of the porous carbon skeleton. The preparation method comprises a step of growing the uniformly-distributed metal hydroxide particles in a limited domain in the holes of the porous carbon skeleton with 1-to-10-nm pore structure. According to the invention, the varieties of catalysts used for water oxidation are enriched, and the high-efficiency universal composite material preparation method is provided; and the method has low cost, is easy for industrial scaling-up, effectively promotes research and performance improvement of water oxidation, accelerates development and industrialization of new energy and energy storage devices related to water oxidation and enables sustainable development to be feasible.