Density functional theory was performed to study the reaction mechanism of the reaction of FC(O)O2 with NO. The geometric configurations of reactants, intermediates, transition states and products were optimized by B3LYP method at 6-311G(d) level. The energies of stationary points along the pathway were also calculated. Intermediates and transition states were confirmed by the results of vibrational analysis. From the results of the mechanism of the reaction of FC(O)O2 with NO, we found that the reaction of FC(O)O2+NO has four pathways and several steps. Comparing the four pathways activation energies, we can find that the pathway FC(O)O2+NO→bM→bT→FC(O)O+NO2 is the main reaction pathway and the main products are FC(O)O radical and NO2, which is in good agreement with the result reported in the literature.