Microwave sensitization including microwave and activated carbon can significantly improve Fenton oxidation ability. To study the generation mechanism of product and the relationship between microwave, AC and H₂O₂, materials of different sizes and different Fe content were made, several control experiment were carried out to prove the possible generation ways of O₂, CO₂ NO₂₃ and the effect of microwave and AC, the mechanism of NO catalytic oxidation by Fenton reagent combined with microwave sensitization were obtained at last. The results indicate that the microwave sensitization can increase the NO removal efficiency from 33.1% to 46.3%, increase O₂ content from 6.9% to 18.6%, and produce 68×10^-6 CO. O₂ generates through AC's absorption and catalysis of Fe²⁺. C and NO can only be oxidized into CO and NO₂ by the OH, HO₂ produced by Fenton reaction. Microwave can intensify all possible reactions in the reagent, the developed pore structure is prerequisite of microwave sensitization of AC, and part of the Fe included in AC joins in the Fenton reagent.