Abstract:  On the basis of improving adsorption capacity of the activated carbon (AC) modified by high concentration HNO₃ and KOH solution, a special microwave device was designed for further modification of AC by the heat treatment, and a kind of highly active carbon sorbent used for combined flue gas desulfurization and denitrification was prepared. Through the adsorption experiment in the simulating flue gas using modified AC, it is found that the modified AC under microwave irradiation evidently increases the adsorption capacity of SO₂, and the best removal efficiency can be obtained with the AC pretreated by KOH solution and modified by microwave. The experiments indicate that the AC pretreated by high concentration HNO₃ and microwave irradiation has a better removal of NO with the adsorption capacity of 36.8×10^-3. The SEM pictures show the numbers of the micropores increase clearly, which is in favor of removal of pollutants. The mechanism of removing SO₂ and NO with various modified methods was analyzed simply in the paper.