The catalytic conversions of diesel exhausting particulates (DEP) are studied in this paper. The oxidation catalysts, carried by Y-Al,O, pellets, are prepared with the method of impregnation. By use of thermo-gravimetric analysis (TGA) technique, the catalytic abilities of these catalysts are studied and the igniting characteristics of DEP are determined. A mathematical method is introduced to process TGA experimental data furtherly. Some equations have been derived to evaluate the kinetic parameters of the oxidation reaction of DEP. By comparing the activation energy (Ea) of the reaction and the igniting temperature (Ti) of DEP, the catalytic activities of the oxidation catalysts are evaluated.