MDEA compound absorbent for acid gas separation and separation method

The invention discloses an MDEA compound absorbent for acid gas separation and a separation method, and belongs to the technical field of gas separation. The MDEA compound absorbent comprises MDEA, alcohols immiscible with water and water, wherein the weight percentage of MDEA is 10-60%, the weight percentage of alcohols immiscible with water is 10-60%, and the weight percentage of water is 10%-80%; due to the solubilization assisting effect of MDEA, the compound absorbent has a homogeneous phase before absorbing acid gas, and is formed into liquid-liquid phases after absorbing acid gas, the upper liquid phase is the barren liquid phase loaded with acid gas, the lower liquid phase is the rich liquid phase loaded with acid gas, and only the rich liquid phase enters a desorption unit, so that the desorption energy consumption is reduced. The compound absorbent is formed into liquid-liquid phases after absorbing acid gas, the liquid-liquid phases are easy to separate, and the composition proportion of the absorbent is adjusted to adapt to the optimal volume ratio of the upper liquid phase and the lower liquid phase and loading capacity of the absorbent in the process, so that amount of the rich liquid phase entering the desorption unit is reduced, and the desorption energy consumption is reduced.