SO₂ absorption of Ca(OH)₂ and NaOH was investigated in wet absorption process of flue gas desulfurization (FGD) to remove SO₂ in emission gas of incineration. When using Ca(OH)₂ absorbent, SO₂ flowrate and concentration were varied to observe effects of emission-gas conditions. In addition, effects of absorbent conditions were examined, where temperature and amount of Ca(OH)₂ were varied and Ca(OH)₂ and NaOH absorbents were used to compare in absorbent type. Increase of SO₂ flowrate and concentration decreased starting detection time of unabsorbed SO₂ on Ca(OH)₂, but could insignificantly affect total amount of SO₂ absorbed by Ca(OH)₂. Although temperature of Ca(OH)₂ solution did not influence starting detection time of unabsorbed SO₂ on Ca(OH)₂, increase of the temperature decreased total amount of SO₂ absorbed on the absorbent. Furthermore, more amount of Ca(OH)₂ solution increased the starting detection time and total absorbed SO₂ volume. On the other hand, absorbed SO₂ amount per weight of Ca(OH)₂ solid lowered with increasing Ca(OH)₂ concentration. Finally, the absorbed SO₂ amount was higher on Ca(OH)₂ than NaOH. Thus, this study provided the basic information for decision of appropriate absorbent type and the quantity of absorbent in order to use wet absorption process to reduce SO₂ under the field operation conditions.