Abstract: Chemical absorption is currently the most mature technology for CO₂ capture from flue gas. However, this technology hasn't been put into commercial application due to the high regeneration energy. Biphasic absorbent is a promising solution as it can significantly reduce the regeneration energy. This paper studied the CO₂ absorption behavior of the dimethylacetamide (DMAC)/ diethylenetriamine (DETA) biphasic absorbent, and measured the composition distribution, absorption and desorption heat, and cyclic loading, which is important for the application of the DMAC/DETA for CO₂ capture. When DMAC/DETA absorbs CO₂, liquid-liquid phase separation occurs, and CO₂ is enriched in the lower phase. Under the total CO₂ load of 1.3915 mol/mol, the rich phase accounts for about 45%, and the composition is 35% DETA+6% DMAC aqueous solution. Under the condition of 120℃ desorption, compared with 20% MEA, the unit CO₂ desorption enthalpy change of DMAC/DETA decreased by 63.3%; compared with the overall desorption, the unit CO₂ desorption enthalpy change of rich phase desorption decreased by 21.4%. The DMAC/DETA absorbent has good cyclic stability, and the desorption rate at 110℃ maintains at about 67.5%.