To elucidate the adsorption/ decomposition behavior of H2O2 and oxidation behavior of NO in H2O2 / Fe2(MoO4) 3 denitrificationsystem, density functional theory (DFT) calculations were performed to investigate the individual adsorption and co-adsorption characteristics of H2O2 and NO on Fe2(MoO4) 3 surface for the first time. The adsorption energies, Mulliken population, and oxidation pathwayswere systematically analyzed to reveal the mechanism of catalytical decomposition of H2 O2 and NO oxidation. The results show thatH2O2 can be easily decomposed into reactive radicals on Fe2(MoO4) 3 surface, while NO is adsorbed in molecular form. In the case of coadsorption, H2 O2 preferentially adsorbs on the catalyst surface and undergoes decomposition process. NO is subsequently oxidized toHNO2 / NO2 by the hydroxyl group/ oxygen atom generated from H2O2 decomposition. The oxidation products HNO2 / NO2 are only bonded tothe catalyst surface via hydrogen bond and can easily enter the mainstream flue gas under flow disturbance, thus reducing the depositionpossibility of nitrate on catalyst surface. This study unravels the micro mechanism of H2O2 adsorption/ decomposition and NO oxidation onFe2(MoO4) 3 surface, providing theoretical guidance for designing heterogeneous Fenton-like denitrification system with high catalytic activity and excellent stability.