The invention relates to a smoke denitrifier with a scale inhibition function, which comprises 1 to 50 weight percent of urea, 0.01 to 0.1 weight percent of scale inhibitor and the balance of water, wherein the scale inhibitor consists of 30 to 40 weight percent of polyaspartate, 20 to 35 weight percent of sodium gluconate and 10 to 20 weight percent of hydrolytic polymaleic anhydride. The smoke denitrifier has denitrification and scale inhibition functions; moreover, when the smoke denitrifier is used, the hardware investment of a silicon-controlled switch (SCR) system of a power plant can be reduced and the labor intensity of workers can be reduced.