[Objective] The aim was to study the breeding of high cellulase yielding strain induced by chemical mutagens.[Method] One strain of Trichoderma viride F1 was taken for original strain.After treated with NTG,DES and LiCl,the high cellulase-producing strain named L6 was bred.[Result] Under suitable conditions,the CMCase activity of L6 increased by 35.7% compared with that of the original strain.[Conclusion] Chemical mutation was the effective means to induce microorganism and breed superior strain.