Abstract: A method of removing NO.sub.x and SO.sub.2 from an exhaust gas containing NO.sub.x and SO.sub.2 which comprises contacting an exhaust gas containing NO.sub.x and SO.sub.2 with an aqueous solution containing M.sub.2 SO.sub.3, an iron ion and an aminopolycarboxylic acid to absorb NO.sub.x and SO.sub.2 in the aqueous solution and treating the resulting absorbing solution while preventing a contact of the solution with the exhaust gas, thereby to form M.sub.2 S.sub.2 O.sub.6 in the absorbing solution and reducing NO.sub.x to N.sub.2. The M.sub.2 S.sub.2 O.sub.6 formed in the absorbing solution can be easily removed by crystallization separation. With such method, NO.sub.x and SO.sub.2 can be removed from exhaust gases at high rates and the absorbing solution can be easily regenerated and recycled to the absorbing zone.