Abstract: Using one bud and one leaf （hereinafter referred to as leaf） as raw materials, this study investigated the changes in biochemical components during the withering process of fresh leaves of Ziyang population species, and indoor natural withering was carried out under conditions of temperature 20~25 ℃ and relative humidity of 75%~80%. The thickness of the spread leaves was 2~3 cm. Samples were taken and solidified by microwave at 0, 8, 10, 12, 14, 16, 18, and 20 hours of withering, and the biochemical components content was measured by grinding. During the withering process of fresh leaves in the Ziyang population species, the water extract content of withered leaves showed a trend of first increasing and then decreasing, but the difference in content was not significant at different withering times;the content of tea polyphenols in withered leaves first decreased and then increased, but overall showed a downward trend. There was no significant difference in tea polyphenol content between different withering times from 8 hours to 20 hours, and the content tended to stabilize. During the entire withering period, the content of tea polyphenols decreased by 5.60%;the soluble sugar content in withered leaves showed a trend of first decreasing and then increasing. Compared with withered leaves for 12 hours, the soluble sugar content in withered leaves for 20 hours increased by 14.63%;the content of free amino acids in withered leaves showed a trend of first increasing and then decreasing. From the beginning of withering to the end of withering, the content of free amino acids increased by 18.02%;under conditions of temperature of 20~25 ℃ and relative humidity of 75%~80%, the fresh leaves of the Ziyang population species reached a moderate degree of withering between 18 and 20 hours. During the withering process, water served as both a reactant and a reaction medium in the process of biochemical composition changes. The changes in water content of withered leaves had a significant impact on the biochemical composition of tea, and reasonable measures should be taken to coordinate the changes in water content and biochemical components of withered leaves, so as to achieve the optimal degree of withering.

Key words: Ziyang population species, withering process, fresh leaves, biochemical components, dynamic changes