Test bench for 186FA diesel engine was built to collect the particles emitted by diesel engine under different working conditions. Then nitrogen adsorption method was used to measure the characteristic parameters such as specific surface area, average pore radius and pore volume. The oxidation characteristics of particle were analyzed by thermogravimetry and Coast-Redfern integration, and the analysis of relationship was further conducted between the characteristic parameters of particle structure and the activation energy of particle oxidation was analyzed by the method of partial least square regression analysis (PLS). The results showed that the specific surface area and pore volume of particles increased, the average pore radius decreased, the oxidation characteristic temperature advanced, the first-stage activation energy (E₁) increased slightly, and the second-stage activation energy (E₂) decreased significantly with the increase of diesel engine speed. The specific surface area, pore volume and average pore radius of particles had the same influence weight on E₂, and the established PLS model could predict E₂ accurately with a maximum error of 3.4%.