Abstract: You 510,a natural hybrid offspring of Lechang Baimaocha cultivars,was the tea plant from which the leaves were used for this study.The major biochemical changes in the leaves during processing and their possible relationship with the resulting white tea quality were investigated in order to optimize the processing technology.During the tea-making process,the picked fresh leaves were first withered 56 h,then dried.The white tea typically smells and tastes sweet with the characteristic aroma.The soluble solid content of the tea's water extract reached a maximum at 24th hour of wilting.It,then,descended significantly with continued wilting.The total polyphenols in the tea leaves peaked after wilting for 12 h,followed by a gradual decline with wilting.The caffeine content in the leaves reached the highest at 48 h,without appreciable fluctuations during the entire wilting process.Content of catechins,such as EC,EGC and EGCG,was at its highest after wilting for 12 h.On the other hand,GA content was at its highest at 48 h,and both C and ECG declined with wilting progressed.The total amino acids of the withered leaves significantly increased initially to peak at 12 h,then decreased to a minimum at 48 h.Theanine appeared to change in a similar manner.The content of GABA was found to significantly and continuously increase throughout the process.