Abstract: The ozone layer absorbs more than 90% UV-C(100295 nm) and UV-B(295320 nm) which are harmful for the livings on the earth an let the living things exist and multiply safely. So the depletion of the ozone layer and mechanism of the ozone hole have been the fatefully and globally environmental problems. Nowadays, many chemicals depleting ozone, such as CH4, Cl, F, NH2and so on, have been discussed by theoretical or experimental methods. Theab initio MP2 method has been employed to study the Criegee reaction mechanism of CH2CHF with ozone at the 6-311++G**base level, to optimize the geometry configurations of reactants, products, intermediates, and transition states. Reaction various compounds energies have been calculated using the QCISD(T) method at the 6-311++G**base sets level. Intermediates and transition states of the reaction were verified by the frequency analysis and the intrinsic reaction coordinate (IRC) calculationwas also performed forgetting the further credible results. The results showthat the Criegee reaction mechanismof CH2CHFwith ozone is reasonable. Thatmeans the reaction is a three-step process and the second step is the controllingstep, namely, M2→TS2→M3. The barriers ofthe controllingstep duringthe CH2CHFwithozone reaction are not high, only 38.22 kJ/mol. That is to say, the CH2CHFwith ozone reaction has a strong activity and the fluoro-ethylene may deplete ozone. Thus, such a research has the greatly theoretical significance for protecting the ozone layer.