Abstract: To evaluate the stability of an amine absorbent for the absorption-desorption cycle of low-flow, low-concentration, low-partial-pressure CO₂, the ratio of apparent cycle capacity to maximum cycle capacity and the capacity of 20 cycles were used as two performance parameters for the absorption stability of organic amine absorbent, the absorption and desorption properties, the ratio of apparent cycle capacity to the maximum cycle capacity and the cycle capacity of 20 absorption-desorption cycles of Ethanolamine (MEA), Triethylenetetramine (TETA), N–Methyldiethanolamine (MDEA) and MDEA + TETA were studied. The result shows that the ratio of apparent cycle capacity to maximum cycle capacity can directly reflect the differences between the CO₂ absorption properties in limited conditions and the maximum absorption properties. The capacity of 20 cycles reflects the changes of amine absorbents’ ability to transport CO₂ during the absorption-desorption cycle. The ratio of the apparent cycle capacity to the maximum cycle capacity of MDEA/TETA mixed absorbent is the highest, reaching 78.10%, and it can keep a higher cycle capacity in the multi-absorption-desorption process. The maximum capacity of MDEA/TETA mixed absorbent in the 20 cycles is 0.75 mol CO₂/mol amine, which is relatively stable thus has a good potential for capturing CO₂ in flue gas from industrial fossil fuel combustion.