The exhaust flue gas from a circulating fluidized bed boiler with low nitrogen combustion should be cleaned once again when NOx concentration exceeds the emission limit. Flue gas purification process mainly includes SNCR denitrification and SCR denitrification.In order to identify the most economical and suitable denitrification technology for circulating fluidized bed combustion conditions，the techno-economic analysis model was suggested and the techno-economic index for two cases was predicted under the condition of full load. The results indicate that reductant price，catalyst price and annual operating time are the main factors affecting the denitrification cost. The price of urea is the most sensitive to the cost of SNCR denitrification，and the sensitivity of liquid ammonia to the cost of SCR denitrification is greater than that of the catalyst. When operating cost and total cost of SNCR denitrification technology are relatively low，NOx concentration can be required below 140 mg/m3 and 228 mg/m3. Based on the inlet NOx concentration of 200 mg/m3，the economic comparison between two cases shows that when the price of urea is lower than 3 402 yuan/ton，the total cost of SNCR denitrification technology is lower. When the unit price of liquid ammonia is higher than 3 300 yuan/ton，the total cost of the SNCR denitrification technology is more economical. Within the research fluctuation range of catalyst and annual operating time，the total cost of SNCR denitrification technology is always the lowest and the most economical. SNCR-SCR combined denitration technology has no economic advantage，and the total cost is the highest when the inlet NOx concentration is 151-273 mg/m3. Ultra-low emission circulating fluidized bed boiler technology can improve the economy of SCR denitrification technology and SNCR denitrification technology，and make the advantages of SNCR denitrification technology more prominent.