In the application quantum chemistry computation theory density functional method, in the B3LYP/6-311 G(d, p) level, the research methylene chloride and the ozone reaction mechanism, optimized responded on the channel the reactant reactant, the intermediate, the transient formation and the product geometry configuration, has calculated their energy in the identical level; And through the vibration analysis and in reported the response coordinates (IRC) computation, confirms between them the relevance. The computed result indicated that,The CHCl2 free radical and the ozone have the strong response activeness, also the response thermal reaction is big, responds for the strong exothermic reaction.