Abstract: Small reaction kettles were applied for absorption of H₂S from natural gas using mixed amine solutions composed of the active MDEA and additive DGA and AMP in different proportion using constant pressure absorption method and constant volume absorption method when the total concentration was 2 mol/L. Through analyzing the gas molar concentration, absorption rate, acid gas removal rate and selectivity factor, the mixed amine solution with optimal proportion for selective desulfurization was obtained. The results showed that 2 mol/L MDEA+DGA mixed amine solution had maximum selectivity factor with the optimal molar proportion of 10:3, which had a higher absorption and removal rate for removing H₂S from natural gas and had a lower absorption and removal rate for removing CO₂ from natural gas. 2 mol/L MDEA+AMP mixed amine solution had maximum selectivity factor with the optimal molar proportion of 10:3, which had a higher absorption and removal rate for removing H₂S from natural gas and had a lower absorption and removal rate for removing CO₂ from natural gas.