Abstract: Exogenous catalase was added in water extract solution of low- grade green tea to transform it into instant black tea by liquid state fermentation,the effects of enzyme types and addition rates on the pigment composition of black tea infusion were investigated; and fermentation technology was optimized by reference to standard of top quality black tea. Result showed that the optimized conditions were: catalase addition rate was0.25 U / m L,fermentation temperature at 45 ℃,p H6,for 2 h. Pretreatment of the green tea extract with polyphenol oxidase( addition rate 0.05 U / m L,temperature 40 ℃,p H5,time 1.5 h) previous to the addition of catalase produced better pigment composition of black tea than addition of catalase along,indicating that synergetic action existed between the two enzymes.