Abstract: For investigating the essential aspect of formic acid/H_2O_2 oxidation desulfurization system, a semi-empirical molecular orbital theory and parametric model methods(PM3) were used to calculate the quantum chemical properties of several typical sulfur compounds in petroleum products and their corresponding sulfone compounds. Relationship between the reaction constants in H_2O_2/fomic acid and electron charge of sulfur atoms was obtained by linear regression. In order to study oxidation kinetic index of the oxidation desulfurizaiton reaction, dibenzothiophene was employed as model compound for obtaining the oxidation kinetic data. Results show that the activation energy of the reaction is 60 kJ/mol.