Abstract: Four extracellular enzyme activities in Pleurotus ostreatus and Lentinula edodes mycelium were determined by adding to different dosage additional 6-benzyl aminopurine (6-BA) in potato liquid medium. The results showed that low concentration of 6-BA promoted their activities and high concentration inhibited their activities. For Pleurotus ostreatus and Lentinula edodes, the optimum concentration of 6-BA to activate their extracellular amylase, carboxymenthel cellulase and catalase was the same which was 1.5 mg/100 mLculture solution. But, the optimum concentration for their extracellular protease was 0.5 mg/100 mLculture solution.