The sintering flue gas emission limit is becoming more and more strict, similar to the ultra-low emission standard of themal power industry, it is speculated that the ultra-low emission standard of flue gas pollutants is imperative. The existing flue gas purification technologies were described in this paper, and the prospective "ultra-low emission" technologies of flue gas purification, such as the source NO_x control technology, the selective catalytic reduction technology and the AC collaborative multi-pollutant purification process etc. were analyzed in terms of their advantages and disadvantages, and some suggestions were also put forward for applicability of each technology.