The combined purification process of "activated carbon desulfurization + low temperature SCR denitration" has been industrially applied in Baosteel Zhanjiang Iron & Steel Co., Ltd. The emission mass concentration of each pollutant is lower than the national ultra-low emission standard limit. In this paper, the main components of the low-temperature SCR denitration system are expounded in detail, the problems of crystal blockage and uneven temperature field during operation are analyzed and solved, which can provide references for the low-temperature SCR denitration technology in the ultra-low emission transformation of flue gas in the sintering process.