Abstract: Flue gas denitration is the inevitable trend of air pollution control. The waste fly ash of coal-fired power plant can oxidize and remove NO_x. In order to further improve the adsorption capacity, fly ash should be properly modified. Mn-Ce high-content iron ash adsorbents were prepared by loading Mn and Ce components with high-content iron ash as matrix after alkali modification. The adsorption performance and denitration mechanism of modified high iron ash were studied by dynamic denitrification experiments. The results show that the high-content iron ash(DMA) is modified by 6 g CaO,0.1 mol Mn(NO_3)_2 and 0.02 mol Ce(NO_3)_3·6 H_2O,and named Mn(4)Ce(2)/Ca-DMA500,which has the highest denitration capacity, and the NO_x removal capacity can reach 823 μg/g. The essential reasons are as follows. First, during the process of preparing adsorbent by mechanical milling and hydration, the vitreous shell in the ash is destroyed and the FeO_x encapsulated in the vitreous body is exposed. The increase of Fe mass fraction contributes to increasing denitrification capacity of the adsorbents. After loading Mn and Ce, MnSiO_3 and Ca_2Fe_2O_5 are formed on the surface of the carrier. Hollow nanostructures composed of polycrystalline MnSiO_3 shells are often used in adsorbents and catalysts. Ca_2Fe_2O_5 has high catalytic oxidation activity due to the existence of a large number of disordered oxygen vacancies, which significantly increases the denitrification efficiency. Secondly, part of Mn exists in the amorphous form in the adsorbent, Mn and Fe/Ce in the adsorbent forms iron-manganese/manganese-cerium solid solutions, thereby improving the denitration ability. When the calcination temperature is 500 ℃,the pores of the adsorbent are evenly distributed, the pore structure is developed, and the specific surface area and pore volume are the best. CaMnSi_2O_6 has a higher degree of crystallization, and its surface impurities are decomposed or desorbed. Therefore, Mn-Ce high-content iron ash has better denitration performance, which is of great significance for flue gas denitration in air pollution control.