The invention relates to a composite oxide modified wet oxidation catalyst and a preparation method thereof. The problems of poor TiO2 forming performance, weak intensity, complicated catalyst preparation process and high cost in the prior art are mainly solved. Composite carriers are formed through adopting titanium oxide, aluminum oxide, silicon oxide and bonding agents, at least one kind of materials selected from Ru, Pt, Ir, Pd and Rh is loaded on the composite carriers, and the technical scheme of the catalyst and the preparation method of the catalyst is formed, the problems are perfectly solved, and the catalyst and the preparation method can be used in the industrial production of wet oxidation catalysts.