Abstract: A molecular modeling study based on density functional theory (DFT) and transition state theory (TST) was performed to investigate the effect of Na on the NO heterogeneous reduction by char; zero point energy correction was considered and the transition states was confirmed by frequency analysis. The results show that Na can effectively promote the adsorption of first NO molecule on to the char. The presence of Na cannot change the reaction steps, but reduce the activation energies of rate-determining steps from 121.04 kJ/mol to 100.62 kJ/mol. Moreover, the presence of Na can increase the pre-exponential factors as well as the reaction rate, meaning more active sites and enhanced catalytic performance of char in NO reduction.