Abstract: The reaction mechanisms of SO₂, NO_x, CO₂ with ammonia solution were described. And the liquid coexisting components related to the desorption of simulated decarburization solution, including (NH₄)₂SO₃, (NH₄)₂SO₄, NH₄NO₃, NaCl, NH₄Cl and (NH₄)₂CO₃, were analyzed. The results show that the desorption of CO₂ is affected by the mass fraction of liquid phase coexistence components, pH of solution and surface tension. Most of liquid coexisting components could reduce CO₂ desorption of decarburization solution. The restraining effect of liquid coexisting components with the mass fraction less than 10% in the decarburization absorbent liquid on CO₂ desorption is as follows: (NH₄)₂SO₃>NH₄NO₃>(NH₄)₂SO₄ >NaCl>(NH₄)₂CO₃. It is necessary to remove the impurities in flue gas before CO₂ capture, because the purities are harmful for CO₂ desorption due to the hazardous effects on the physical and chemical characteristics of decarburization solution.