Abstract: To study the changes of cellulase and main quality components during solar withering,rolling and fermentation of black tea,the fresh leaves of C. sinensis cv Fuzao2 as raw materials was used for manufacturing tea. The activity of β-glucosidase,endo-glucanase,exo-glucanase were detected,and the amount of main quality components such as soluble sugar,catechins,caffeine,free amino acids were also analyzed in processing of black tea. The results showed that the activity of β-glucosidase,the contents of catechins and free amino acids reached the highest level at the end of withering stage(0.091 U(10 min)^-1·mL^-1,97.6 mg/g,38.9315 mg/g),and decreased rapidly at rolling stage,then to be stable. Endoglucanase activity continued to increase from the onset of solar withering to the end of fermentation,increasing dramatically from 0.19 U(10 min)^-1·mL^-1 to 0.51 U(10 min)^-1·mL^-1. The contents of soluble sugar reduced remarkably at rolling and fermentation stage. However,the activity of exo-glucanase and the contents of caffeine had no significant changes during black tea processing.