Hypocrea jecorina (anamorph: Trichoderma reesei) is the main industrial fungi that can produce large amounts of extracellular cellulases and hemicellulases. It also represents a model system to study the mechanism of transcriptional regulation in eukaryotes. The expression of these hydrolases genes in Hypocrea jecorina can be triggered rapidly in the presence of inducers, but differences in the inducing mode of various soluble inducers have been reported. At present, three models have been offered to explain the question of "how an insoluble inducer such as cellulose would initiate the transcription of cellulases?" Moreover, interactions between the identified positive (Xyr1, Ace2, Hap2/3/5) and negative transcriptional regulators (Ace1, Cre1), as well as the interactions between these proteins and the promoters of cellelase and hemicellulase genes have also been primarily characterized. This review focuses on the key factors and the current understanding on the regulation of expression of cellulase and hemicellulase genes in Hypocrea jecorina.