Carbon dioxide and sulfur dioxide were simultaneously absorbed into aqueous 1,8-diamino-p-menthane (DAM) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0-2.0kmol/m3 of DAM, 0.01-0.12mole fraction of CO2, 0.001-0.012mole fraction of SO2, and 298-318K. Absorption data of each gas in the CO2-DAM and SO2-DAM systems are obtained to verify their reaction regimes, based on film theory, respectively, which are used to analyze the simultaneous absorption mechanisms of CO2 and SO2 in the CO2-SO2- DAM systems. In the simultaneous absorption rate of CO2 and SO2 into DAM solution, the absorption of CO2 belongs to the second-order reaction of finite rate and the absorption of SO2 belongs to the instantaneous reaction regime.