Due to the stricter regulations on the emission of pollutants from coal-fired power plants,all coal-fired power plants have installed denitrification devices (SCR) to remove NOx from flue gas in China. Normally,the denitrification efficiency of SCR facility can be 80%-90%. Under the ultra-low emission restriction,the actual denitrification efficiency of SCR operation of some coal-fired boiler is as high as 95%,which will lead to a sharp increase in the difficulty of ammonia escape control. The formation and removal of ammonia hydrogen sulfate in fly ash after SCR denitration of coal-fired power station boilers at home and abroad were reviewed,its formation mechanism and removal methods were analyzed,and its industrial application was prospected. But it is found that the presence of SO3 and H2O in flue gas can promote the adsorption of ammonia in fly ash. The concentration of NH3 and SO3 and coal grade are the main factors affecting the ammonia adsorption on fly ash. The existing fly ash deamination technologies include heating method,oxidation method,water washing method and alkali addition method. At 204 ℃,the removal of ammonia in fly ash is very slow. After treatment for 80 minutes,the ammonia removal rate is less than 50%. The heating method needs to be carried out at 260 ℃,and the energy consumption is high. When the water content in the ash is higher than 3%,the ammonia removal rate is fast,but in the subsequent drying stage,when the water content in the ash drops below 2%,the ammonia removal rate decreases rapidly,and the water washing method will produce additional wastewater;the oxidation method is to select a suitable catalyst and install it behind the SCR Flue gas denitration device and in front of the air preheater to selectively catalyze and oxidize NH3 in the flue gas into N2,so as to effectively remove the escaping NH3 in the flue gas,reduce the generation of NH4HSO4 and reduce the ammonia content of fly ash,but it can not ensure that the oxidant reacts completely with ammonia,resulting in the escape of residual oxidant. Adding calcium base alkali and water to fly ash and stirring can obtain excellent ammonia removal effect. Adding a small amount of water (～2%) and a small amount of alkali (≤2%) to fly ash can reduce the mass fraction of ammonia in fly ash to less than 100 mg/kg. Due to the small amount of water added,the flue gas can be dried after desulfurization of the subsequent unit,and the NH3 generated in the treatment process can be re injected into the SCR Flue gas denitration device or ammonia water. Alkali addition method has low cost and high efficiency. It is an excellent method to remove ammonia from ash. At present,industry standard regarding the ammonia content in fly ash is not issused. Meanwhile,the effect of ammonia in fly ash on environment and its utilization as construction materials still lacks engineering verification testing. At present,the removal of ammonia in fly ash is still in the stage of laboratory research and industrial pilot test. In the future,the detailed economic analysis is also needed to realize its utilization.