Circulating fluidized bed（CFB)boilers have become one of the best commercial technologies of clean coal combustion due to the advantage of inherent low cost of controlling pollutant emission. With the introduction of ultra-low emission standards,CFB combustion technology also faces huge challenges. In order to meet the ultra-low emission standards,the devices for treatment of flue gas are usually used,resulting in a significant increase in the cost of pollution treatment for CFB boiler. How to achieve ultra-low NOx and SO2 emissions of CFB boiler has become the research focus.The existing conventional ultra-low NOx emission technology of CFB,ultra-low SO2 emission technology of CFB,newly developed ultra-low NOx combustion technology of CFB,ultra-low SO2 emission technology in the furnace of CFB and ultra-low NOx and SO2 cooperative control technology of CFB were systematically discussed. The results show that high-efficiency separators cannot only improve the combustion efficiency of CFB,but also is the premise of using ultra-fine limestone for highly efficient desulfurization. The higher the separator efficiency is,the higher the CFB combustion efficiency and ultra-fine limestone desulfurization efficiency is. With the large-scale development of circulating fluidized bed boilers,the cross-section of the furnace is getting larger and larger,so how to achieve the horizontal uniform mixing of ultra-fine limestone in the large furnace becomes the first technical challenge. The technology for controlling a single gas to meet the ultra-low emission is relatively mature,but how to coordinately control NOx and SO2 to meet the ultra-low emission standard has become the second technical challenge. The current ultra-low emission technology in the furnace of CFB can only achieve ultra-low emissions for certain specific fuels,and however for other conventional fuels,whether NOx and SO2 can achieve ultra-low emissions still needs further deep research.