Abstract: Disclosed in the present disclosure are a low energy consumption anhydrous CO2 phase change absorption agent, and a regeneration method and an application thereof, the absorption agent using a unitary diamine with a primary amine (NH2—) and a tertiary amine (—N—), and not containing any other organic solvent, water, and ionic liquid; two alkyl branches are linked to a nitrogen atom of the tertiary amine, forming a certain hydrophobicity; after absorbing the CO2, the diamine changes from a liquid phase to a solid phase, undergoing liquid-solid phase change to form white amino formate crystals.