Abstract: Taking the three-layer catalyst M₂-N₁-N₂ of a coal-fired power plant as an example, the indexes of main chemical composition, specific surface area, trace elements and denitration efficiency were tested, the quality of the existing three-layer catalyst was analyzed and evaluated, and the sequencing of the three-layer catalyst was optimized, to ensure NO_x to meet the emission standard. The results showed that, compared with SCR catalyst N₁/N₂, SCR catalyst M₂ had less chemical composition of CaO and Al₂O₃, which reacted with SO₃ gas in the flue gas to generate less amount of CaSO₄ and Al₂(SO₄)₃, and it was not easy to deposit in the channel. At the same time, trace elements, such as Na, Mg, Fe and K, in the flue gas and fly ash accumulated less on the surface of catalyst M₂ and occupied less effective acid sites. The overall denitration efficiency was tested, and the denitration efficiency of the single-layer SCR catalyst was also explored. The original sequencing three-layer catalyst was optimized to ensure the overall denitration efficiency to meet NO_x emission requirements under the new sequencing. The benefit analysis was carried out from the multi-dimensions of environment, economy and resources. The economic cost accounting under different replacement methods showed that SCR catalyst under the new sequencing could save 4.719 million yuan or 3.3 million yuan for the plant. Moreover, it could save the manufacturing resources of the fresh SCR catalyst, and avoid the links of environmental pollution caused by the manufacture and handling of the SCR catalyst. SCR catalyst recycled would also prolong the life span of the catalyst.