▎ 摘　　要

NOVELTY - A preparation method of carbon-based metal single atom catalyst in the cycloaddition reaction of carbon dioxide comprises (S1) mixing the carbon source, nitrogen source and metal salt to obtain a mixture, where the carbon source acts as carrier and the nitrogen source acts as ligand, (S2) ball milling the mixture obtained in step (S1) to obtain a mixed intermediate and (S3) heating the mixed intermediate under the inert atmosphere using high temperature pyrolysis method to uniformly disperse the metal single atom in the metal salt on the carrier through the ligand to obtain the product. USE - The method is used for preparing carbon-based metal single atom catalyst which is used in the cycloaddition reaction of carbon dioxide and epoxide (all claimed).