Abstract: Acidic gases such as carbon dioxide (CO₂), carbonyl sulfide (COS), hydrogen sulfide (H₂S), methyl mercaptan(CH₃SH), etc. in feed natural gas need to be removed through alkaline solvent treatment. During the absorption process, the removal rate of H₂S through instantaneous proton mechanism reaction is much faster than that of COS and CO₂. Therefore, although COS content is usually less abundant than H₂S content in the feed gas, conventional techniques for removing H₂S cannot completely and effectively remove COS. Because the chemical structure of COS is similar to that of CO₂, but the absorption rate of CO₂ is much higher than that of COS, it is difficult to retain part of CO₂ and deeply remove COS. At Present, there is a lack of research on the differences between COS and CO₂ absorption mechanisms, which leads to the lack of a theoretical basis for the design of COS selective absorption solvent under the coexistence of a large amount of CO₂. Therefore, the absorption mechanism of COS needs to be further studied. The research progress on the mechanism of CO₂ and COS absorption in organic amine solutions was summarized, and the following understandings are put forward. Firstly, in the aspect of mechanism research, it is generally believed that the absorption mechanism of COS in primary and secondary alkanolamines is the same as that of CO₂ absorption. Secondly, the mechanism of CO₂ absorption by alkanolamine is generally considered to be the removal of CO₂ by the formation of carbaminate, and further thermal decomposition is the release of CO₂ and the recycling of the absorption solution. Thirdly, both COS and CO₂ are linear molecules with very similar physical and chemical properties, making it difficult to selectively absorb COS under the coexistence of COS and CO₂.