As CO2 is the major greenhouse gas, reducing its emission has become an attentive problem in the whole world. It is very important to develop CO2 capture technology for coal-fired power plants. Using ammonia solution to absorb CO2 from the flue gas, which is expected to have advantages of low cost, high efficiency and high absorption load, has become an emerging, hot research area in recent years. However, this technology faces a troublesome problem of ammonia escape. This paper analyzes the mechanism of escaping ammonia; it is also shown the main existing methods to control the escape of ammonia. By comparison, it is concluded that controlling the source of ammonia is feasible. It is also shown that adding some organic additives can inhibit the escape of ammonia and enhance the CO2 removal to some extent at the same time. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.