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Gene expression of fungal cellulolytic enzymes is tightly controlled at the transcriptional level. Key transcription factors such as activator ClrB/CLR2 and XlnR/XYR1, as well as repressor CreA/CRE1 play crucial roles in this process. The putative protein methyltransferase LaeA/LAE1 has also been reported to regulate the gene expression of the cellulolytic enzyme. However, whether the key transcription factors regulate the gene expression of cellulolytic enzymes in the presence of LaeA has not been determined yet.The formation and gene expression of the cellulolytic enzyme was compared among the wild type (WT) and seven mutants, including ΔlaeA (deletion of laeA), OEclrB (clrB overexpression), OEclrBΔlaeA (clrB overexpression with deletion of laeA), OExlnR (xlnR overexpression), OExlnRΔlaeA (xlnR overexpression with deletion of laeA), ΔcreA (deletion of creA), and ΔcreAΔlaeA (double deletion of creA and laeA). Results revealed that LaeA extensively affected the expression of glycoside hydrolase gene. The expression of genes (amy15A, amy13A, cel7A/chb1, cel61A, chi18A, cel3A/bgl1, xyn10A, cel7B/eg1, cel5B/eg2, and cel6A/cbh2) that encoded the top 10 glycoside hydrolase assayed in secretome was remarkably downregulated especially in later phases of prolonged batch cultures. LaeA also regulated the expression of the key transcription factors; specifically, clrB and xlnR expression was dependent on the expression of laeA. When laeA was deleted, the expression of both clrB and xlnR was repressed, whereas creA expression was activated. The relatively high expression of clrB or xlnR in OEclrBΔlaeA or OExlnRΔlaeA could not rescue the impairment of cellulolytic enzyme gene expression through the deletion of laeA, suggesting that LaeA was required for the expression of cellulolytic enzyme gene activated by ClrB and XlnR. In contrast to the remarkable downregulation of prominent cellulase and hemicellulase by the deletion of laeA, the extracellular β-xylosidase formation was an exception. The extracellular β-xylosidase activities improved over fivefold in the OExlnRΔlaeA mutant compared with that of WT, and the expression of prominent β-xylosidase gene xyl3A was activated remarkably, which has potential applications in the production of more β-xylosidase.