Density functional theory was used to study the mechanism of the reaction of FC(O)O with NO. The geometric configurations of reactants, intermediates, transition states and products were optimized by B3LYP method at 6-311G(d,p) level. The energies of stationary points along the pathway were calculated at CCSD(T) level. Intermediates and transition states were confirmed by the results of vibrational analysis. From the results of the reaction mechanism of the reaction of FC(O)O with NO, one can see that the reaction of FC(O)O+NO has four pathways and several steps. Comparing the four pathways’activation energies, one can find that the pathway FC(O)O+NO→M3→TS6→M5→FNO+CO2 is the main reaction pathway and FNO radical and CO2 are the main products, which is in good agreement with the result reported in the literature.