The migration routes of ammonia escaped from the denitrator in flue gas purification system in thermal power plants are introduced. The dissolution equilibrium and material balance of the escaped ammonia in wet limestone desulfurization system are analyzed. Moreover

the conversion of ammonium ion and the possible ways of its migration in three kinds of desulfurization waste water treatment process are also discussed. The results show that

it is difficult to avoid the ammonia escaping from the denitrator

the escaped ammonia is absorbed in the desulfurization tower and converted to ammonium ion which is one of the main sources of that in desulfurization wastewater. In the treatment of desulfurization wastewater with high ammonia nitrogen content

the problem of ammonia volatilization should be fully considered and treated when realizing zero discharge treatment by adding alkali to increase the pH value and evaporating crystallization process of high temperature flue gas.