In this work, we investigated the absorption characteristics of SO₂ and the effect of inhibitors on the desulfurization performances of Na₂SO₃. The results showed that the NO₂ had a competitive effect with SO₂ on SO₃2- which resulted in a significant decrease in the absorption capacity of SO₂. O₂ in the flue gas could decrease the absorption capacity of SO₂ due to the oxidation of Na₂SO₃. Besides, Na₂S₂O₃ had more excellent inhibiting effect on the oxidation of SO₃2-; the inhibition mechanism is understood on the basis of the free radical chain reaction, whereby S₂O₃2- combined with the sulfite free radical to form an inert substance, thus, quenching the reaction of free radical with the dissolved oxygen and invariably inhibiting the oxidation of SO₃2-. Furthermore, the intrinsic and the apparent oxidation kinetics of Na₂SO₃ oxidation process with Na₂S₂O₃ were investigated to explain the relationships between consumption rates of SO₃2- and the absorption capacities of SO₂ under different components in flue gas and absorption solution.