The invention relates to a catalytic wet oxidation method of flue gas desulfurization waste liquor. In the presence of a catalyst, flue gas desulfurization waste liquor contacts air to oxidate sulfite into sulfate, wherein the catalyst uses nano TiO2 as a supporter, the active component of the catalyst is one or more of noble metal elements Pt, Pd, Ru and Rh, and the assistant is one or more of rare earth metal elements La, Ce, Pr and Nd. The catalyst comprises the following components in percentage by weight: 0.05-0.5% of noble metal element and 1-10% of rare earth metal element. The mass ratio of the rare earth metal element to the noble metal element is 10-200. By adopting the proper catalyst, the method provided by the invention lowers the cost of the catalyst on the premise of enhancing the reactivity; and the catalyst has the advantages of high stability and no secondary pollution.