In this paper,a 1400 bp gene from mycelium of industrial production strain Trichoderma viride Sn-9106 was cloned using RT-PCR with total RNA as templates.Compared with the sequence of E00390 endoglucanase from Genbank,the proportion of homologous amino acids was 91%.The EG I gene was constructed into expression vector of pESC and the recombinant EG I mature protein was expressed in Saccheromyces cerevisia strain Fm135a under the control of GAL10 promoter.After primary purification,specific activity of the recombinant endoglucanase was 2.45 U/mg.The SDS–PAGE analysis showed a band with apparent molecular weight of about 49 kD.