During the liquid-phase oxidation of p-xylene, over-oxidation of reactant, intermediates and solvent to carbon dioxide and carbon monoxide is generally known as the burning side reaction. Batch and semi-continuous experiments were carried Out, and the experimental data of the burning side reaction were analyzed and reported in this paper. The results showed that the rates of burning side reactions were proportional to the rates of the main reaction, but decreased,with the increasing concentrations of reactant and intermediates. The inter-simulative and competitive relationship between the burning side reaction and the main reaction was confirmed, and the rates of the burning side reaction Could be described with some key indexes of the main reaction. According to the mechanism of the side reactions and the kinetics model of main reaction which were proposed and tested in the previous papers, a kinetic model of the burning side reactions involving sonic key indexes of the main reaction was developed, and the parameters were determined by data fitting of the COx rat curves. The obtained kinetic model Could describe the burning side reactions adequately.