Abstract:The compound enzymes were prepared from fresh tea leaves， and instant green tea was enzymatic oxidized by the compound enzymes in this article. The oxidation degree of catechins in instant green tea was set as evaluation index， single factor experiment was used to analyze the influence of five factors including concen－ tration of compound enzymes， concentration of substrate， pH， temperature and reaction time on the effect of enzymatic oxidation， and the best conditions of enzymatic oxidation were optimized by orthogonal test. The re－ sults showed that the optimal enzymatic oxidation conditions of instant green tea as follow： in the enzymatic re－ action system， the concentration of compound enzymes was 2.0 %， concentration of substrate was 0.5 %， the pH of system was 3.5， the temperature was 45 ℃ and the reaction time was 2.5 h. Under the conditions， the oxi－ dation degree of catechins was high to 34.79 %. There existed four maximum spectral absorption peaks at 265， 300， 380 nm and 460 nm in the enzymatic oxidation products of instant green tea， and that was similar to the absorption spectrum of tea pigment in black tea. The content of theaflavins in enzymatic oxidation products of in－ stant green tea was high to 14.68 %， and it was higher than that of black tea extract.