The mechanism and dynamical properties for the reaction of HCCO radicals with NO were investigated theoretically. The minimum energy paths(MEP) of the reaction were calculated by using the density functional theory(DFT) at the B3LYP/6-311+G ** level, and the energies along the MEP were further refined at the QCISD(T)/6-311+G ** level. It is found that the reaction mechanism of the title reaction involves three channels, producing HCNO+CO, HONC+CO and HCN+CO 2 products, respectively. Channel 1 is the most favorable path. The rate constant for channel 1 were calculated over a temperature range of 800—2500 K by using the canonical variational transition-state theory(CVT). The rate constant for the main path is negatively dependent on temperature, which is a characteristic of radical reactions with negative activation energy, and the variational effect for the rate constant calculation is small in the whole temperature range. The minimum energy paths (MEP) of the reaction were calculated by using the density functional theory (DFT) at the B3LYP / 6-311 + G ** level , and the energies along the MEP were further refined at the QCISD (T) / 6-311 + G ** level. It is found that the reaction mechanism of the title reaction involves three channels, producing HCNO + CO, HONC + CO and The rate constant for channel 1 were calculated over a temperature range of 800-2500 K by using the canonical variational transition-state theory (CVT). The rate constant for the main path is negatively dependent on temperature, which is a characteristic of radical reactions with negative activation energy, and the variational effect for the rate constant calculation is small in the whole temperature range.