Abstract: In order to breed new thermo- tolerant strains of Lentinula edodes, the protoplasts of Hu Nong 2 ( original strain) were exposed to ultra- violet ray and the mutants were screened through mycelia recover ability after being treated at 47℃ for two hours.Totally 24 thermo- tolerant mutant strains of Hu Nong 2 were obtained.The growth rate of mycelia in sawdust medium during constant temperature process ( 25℃) , high temperature process ( 30℃) and recover temperature process ( 25℃) were determined. The fruiting bodies of the mutants were collected at 25℃.Comprehensive analysis of growth rate and biological characteristics of fruiting bodies showed that Hu Nong 2mutants N14, N15, N21 and N24 had faster growth rate during recover temperature process than Hu Nong 2 and at the same time these mutants showed better biological characteristics of fruiting bodies in single mushroom weight, cap thickness and cap diameter than Hu Nong 2.These results indicated that the four mutants of Hu Nong 2 had good comprehensive biological characteristics.