Abstract: Based on the density functional theory of quantum chemistry and transition state theory, reaction mechanism of heterogeneous reaction of ketone char with NO and oxygen desorption of the products were examined. The results indicate that NO is more easily adsorbed on surface of the ketone char. The ketone group of armchair enhances the char heterogeneous reduction of NO; On account of oxygen concentration in the ketone of zigzag char may not be within the range where is beneficial to reduction of NO, the energy barrier value of heterogeneous reduction of ketone coal char and NO (495.45kJ/mol) is higher than that of the pure carbon-based char and NO (331.32 kJ/mol). Without the presence of CO, the P1 of intermediate products is more prone to oxygen desorption than the pure carbon-based char, and surface defects are produced. With the presence of CO, the ketone char provides surface free active sites for the oxygen desorption process, which reduces energy barrier of the process.