The unique quality and health benefits of ripened Puer tea stem from its microbial post -fermentation process. Phenolic compounds undergo significant transformation during this process to form the material basis for their flavor and functional characteristics. This article reviews the changes in phenolic compounds including catechins degraded by microbial extracellular enzymes and converted into gallic acid， theaflavins， and novel biologically active derivatives such as Puer catechins， carboxymethylated catechins， and Teadenol A through the oxidation， polymerization， cleavage， and other reactions during the fermentation process of ripened Puer tea to study the changes in phenolic compounds during the fermentation process of ripened Puer tea and analyze the mechanism of quality formation. The total amount of flavonoids remains stable， and the hydrolysis of glycoside in flavonoids releases quercetin and other aglycones. The composition of phenolic acids changes significantly， with an increase in the content of gallic acid and tannic acid further being metabolized into aroma-contributing compounds like methoxybenzenes. Furthermore， theaflavins and thearubigins formed during fermentation are subsequently converted into theabrownins via enzymatic polymerization and complexation with non-phenolic components such as polysaccharides and proteins. These transformations underpin the characteristic reddish-brown infusion color， mellow taste， and distinctively aged flavor of ripened Puer tea and are closely associated with its health benefits including the regulation of gut microbiota， antioxidant activity， and metabolic modulation. Studies in the future should integrate multi-omics to deeply analyze the interactions between microorganisms and phenolic metabolism， accurately identify the structure-activity relationships of key bioactive derivatives to comprehensively elucidate the quality formation and functional characteristics of ripened Puer tea.