Abstract: The strains of Flammulina velutipes are cultured with rice straw. The change of lignocellulose in medium and the transformational law of extracellular enzyme activity related to the degradation of major medium constituent at different culture stages are studied. Results show that the degradation of cellulose and hemicellulose are occurred in reproductive period primarily and the degradation of lignin is expediter in vegetative growth period. Enzymes related to the degradation of cellulose are more stable from cultivation prophase to the end. Enzymes related to the degradation of lignin are much higher at cultivation prophase. The activity of xylanase is lower and is higher at the phase of fruiting body occurred. The activity peak of amylase occurred in cultivation prophase. The activity of proteases are higher at cultivation prophase and the phase of fruiting body occurred，however，the activity is more stable.