The formation mechanism of nitrogen oxides was analyzed, and the design idea of denitration calciner was formed. The design idea of denitration calciner is to increase the height of the tertiary air duct, reduce the position of coal feeding point in the calciner, form an anoxic area in the middle, and create a denitration reduction area in the lower part of the calciner, and finally reduce all the nitrogen oxides generated in the rotary kiln. The actual transformation project shows that the emission concentration of nitrogen oxides combined with SNCR system can be controlled within 50mg/Nm³, and the consumption of ammonia water is greatly reduced.