The microorganisms in the samples of pile-fermented Tibetan tea were isolated and purified under the high temperature including 45 ℃ and 60 ℃ to study the effects of thermophilic bacteria on the formation of quality in Tibetan tea.7 thermophilic bacteria were obtained and identified as the genera Heyndrickxia，Brevibacillus，and Terribacillus with morphological and molecular biological methods.They were inoculated into green tea for the solid-state fermentation of single strain under the constant temperature.The results of evaluation showed that the aroma of each treated tea sample in the experiment varied from “chestnut aroma” to “aged aroma” and then to “stuffy taste” during the process of pile-fermentation.Thermophilic bacteria had a certain effect on the taste，resulting in the flavor changing from “strong” to “mellow” and then to “smooth” during the process of pile-fermentation，with a “smooth” and “refreshing” taste.The results of biochemical testing showed that the content of tea polyphenols had a trend of decreasing during the process of pile-fermentation.Bacillus subtilis and the high concentration of Bacillus subtilis contributed to the degradation of tea polyphenols，which may be the reason for the “smooth” taste.The content of free amino acids had a trend of first increasing and then decreasing，but mainly due to the effects of hot and humid.The content of soluble sugar had a trend of first increasing and then decreasing，and then increasing again.The total amount of catechins changed in line with the trend of tea polyphenols.The content of gallic acid in all treatments increased at the end of pile-fermentation，while the content of other components generally decreased.