The invention relates to an oxidant catalyst recycle method, wherein in the reaction solvent with low-order carboxyl acid of fatty group, with heavy metal catalyst and bromine catalyst, it uses oxygenmolecule to oxidize the alkyl aromatic compound to produce the carboxyl acid in aromatic group, to recycle the oxidant catalyst with high recycle ratio; and when heating and concentrating the oxidantreaction mother liquid, mixing and heating said concentrated object; then mixing and granulation the hot slurry, to form granulation slurry; the heating process and granulation process are treated inmixing rove, to separate the solid and liquid of granulation slurry, to recycle separated catalyst water solution.