Screening and identification of strains with high-yield lignocellulose-degrading enzymes are of great significance for the comprehensive utilization of corn stalk biomass resources. Three strains CM12, CM13 and CM16 obtained before using protoplast mutagenesis technique were used as experimental materials. Preliminary screening of dominant mutant strains was carried out by antagonism test and growth rate test. Then, screening of the mutant strains with high-yield lignocellulose-degrading enzymes were carried out through the determination of laccase, manganese peroxidase, xylanase and cellulase activities, and its identification was performed by ITS-PCR technology. The results showed that the three strains were antagonistic to the control strain. Strain CM13 had the highest growth rate in PDA solid medium, higher than that of strain CM12, strain CM16 and the control strain. Strain CM13 in pure corn stalk liquid medium had the highest laccase, manganese peroxidase, xylanase and cellulase activities, reaching 121.23 U/L, 144.11 U/L and 793.38 U/L and 238.92 U/L, respectively , which increased by 13.07%, 12.90%, 19.93% and 30.22%, respectively, compared with the control strain. ITS-PCR results showed that strain CM13 mutated at the molecular level.