A dynamic method is employed to study the reaction mechanisms of CH3CH2OCF3 with the hydrogen trioxy(HOOO) radical. In our paper, the geometries and harmonic vibrational frequencies of all the stationary points and minimum energy paths(MEPs) are calculated at the MPW1K/6-31+G(d,p) level of theory, and the energetic information along MEPs is further refined by the CCSD/6-31+G(df,p) level of theory. The rate constants are evaluated with the conventional transition-state theory(TST), the canonical variational transition-state theory(CVT), the microcanonical variational transition-state theory(μVT), the CVT coupled with the small-curvature tunneling(SCT) correction(CVT/SCT), and the μVT coupled with the Eckart tunneling correction(μVT/Eckart) based on the ab initio calculations in the temperature range of 200 ~ 3000 K. The theoretical results are important in determining the atmospheric lifetime and the feasible pathways for the loss of HFEs.