Introduction is made to the process of “SDA (Spray Dryer Absorber)+dedusting DeNOx” in this paper.Technical and economical analysis is also made for this project,which shows that the bought-out raw materials and energy cost take majority of the total operating cost of the project.The technical innovation in DeSOx & DeNOx as source control can largely minimize the consumption of ammonia,sodium carbonate and electric power in operation so that the operating cost for this project can be reduced.