In GB 17820-2018 "Natural Gas", the total sulfur limit of the primary commercial gas is specified as 20 mg/m3, which not only brings severe challenges to the upgrading and transformation of desulfurization process in natural gas purification plant, but also brings rare opportunities to the technological progress of gas purification process.Laboratory studies and industrial practices at home and abroad have proved that both activated MDEA and COS hydrolysis processes can make the total sulphur content of the primary commercial gas up to the standard.The former should be used when the total sulphur content is not more than 50 mg/m3, and the hydrolysis process or sulfinol process should be considered when the total sulphur content is above 50 mg/m3.