By means of the density functional theory(DFT) method,the reaction mechanism of the reaction of O(()~3P) with CS_2 was studied at the B3LYP/6-311++G(d,p) level.The geometric configurations of reactants,intermediates,transition states and products were fully optimized.Reactants,intermediates and products were confirmed by the results of vibrational analyses and transition states were verified by the vibrational analysis and IRC calculations.G3B3 method was performed in order to gained the more credible energy data of stationary points along the pathways.On the basis of the results of the reaction mechanism of the reaction of O(()~3P) with CS_2,the study shows that the reaction includes four reaction channels,two of them are the majors.The products of the reaction of CS_2+ O(()~3P) are CS and SO.Our calculated results are in good agreement with the experimental values.