As the main phenolic acid in tea-leaves， gallic acid all showed increasing trends during pile-fermentation， anaerobic fermentation and aging storage， and had closely connection with the hydrolyzation of ester catechins. Due to the secreted extracellular enzymes， such as tannase， Aspergillus niger， Eurotium cristatum， Aspergillus fumigatu， Aspergillus tamarii and Aspergillus pallidofulvus promoted the biosynthesis of gallic acid during the inoculated fermentation. Additionally， Bacillus subtilis and Lactobacillus plantarum both could secrete tannase to enhance gallic acid content in the submerged fermentation. This article reviewed the lasted literature at home and abroad to explore the impacts of microorganisms and released extra-cellular enzymes on gallic acid metabolism. This paper summarized the research progress about gallic acid metabolism during tea-leaves microbial fermentation， and elaborated the biosynthesis mechanism and health efficacy of gallic acid， which would contribute to the research about the regulation mechanism of gallic acid metabolism under effects of microorganisms.