Abstract: Dark tea, as a kind of microorganism fermented tea with important economic and health value, is closely related to microorganisms, and is involved in the productive process of dark tea. In order to clarify the relationship between microbial species and dark tea quality, we reviewed the variation of microbial diversity in the fermentation process. We compared the microbiological differences between different types of dark tea during fermentation period. We explained the changing rule of microorganisms in the pile-fermentation process of dark tea. Bacteria, Mycete and Saccharomycetes were widely propagated in the early, middle and late stage of piling fermentation, and the early stage of bacteria was more. Mycete and Saccharomycetes play dominant roles in the middle and late stage, respectively. By means of the clear advantages of modern identification of bacteria species composition and diversity in microbial taxonomic status of dark tea follow-up study, exploring effects of different microbial assemblages of dark tea quality, strengthening tea pile-fermentation control technology research and deep processing mechanization are important research trend in the future. According to the development experience of the world′s largest tea brand, Lipton Black Tea, we insist on ensuring quality and ensuring stable quality standards. According to uniform production standards, we produce and sell dark tea varieties from different origins in accordance with uniform standards, forming an internationally renowned brand. This is also a reference for the current crackdown on the development of the national dark tea industry.

Key words: dark tea, pile-fermentation, microbial diversity, Eurotium cristatum, tea polyphenol