Abstract: Density functional theory (DFT) B3LYP method was employed to study the mechanism of the reaction of CH₃CF₂O₂ radical and HO₂ radical at the 6-311G、6-311+G(d)、6-311++G(d, p) levels. The results indicate that there are two reaction pathways in this reaction. The main reaction pathway is CH₃CF₂O₂ +HO₂→IM1→TS1→CH₃CF₂OOH+O₂, the corresponding activation energy is 77.21 kJ•mol^－1, and the main products are O₂ and CH₃CF₂OOH. They are in good agreement with the experimental results. The other reaction pathway is CH₃CF₂O + HO₂→IM2→TS2→IM3→TS3→IM4 + IM5→IM4 + TS4→IM4 + OH + O₂→TS5 + OH + O₂→CH₃ + CF₂O + OH + O₂→CH₃OH + CF₂O + O₂, and the corresponding activation energy is 93.42 kJ•mol^－1. The results show that this reaction pathway can also occur, and it is in agreement with the results in literatures.

Key words: Reaction pathway, Transition state, Activation energy, CH₃CF₂O₂