UMP2 method was performed to study the reaction mechanism of CH2 with HNCO.The geometrical configurations of reactants,intermediates,transition states and products were optimized by UMP2 method at the 6-311++G（d,p）level.The energies of stationary points along the pathways were calculated at QCISD（T）/6-311++G（d,p）.Intermediates and transition states were confirmed by the results of vibration analysis and IRC calculation.From the results of the reaction mechanism of CH2 with HNCO,it is shown that in this reaction there exist three pathways,which are CH2（S）+HNCO→IM1→TS1→CH3+NCO;CH2（S）+HNCO→IM2→TS2→CH2CONH,CH2（T）+HNCO→IM3→TS3→CH2NH+CO,and CH2（T）+HNCO→IM3→TS3→CH2NH+CO.
