The cellulolytic enzymes from filamentous fungi are widely used for production of biofuels. Molecular biological engineering of fungal strains has been applied to improve the cellulase production in the recent years. The VIB gene affects production of cellulase and known as a new transcription factor. Based on a fast-growing strain Trichoderma orientalis EU7-22, we constructed two recombinant strains that knockout the VIB gene and overexpressed the VIB gene and the effects of the VIB gene on cellulase production under induction conditions were also investigated. Under the condition of induction by avicel and wheat bran, the cellulase activity of the recombinant -VIB strain was almost undetectable, while that of the +VIB strain was greatly improved. FPAase, CMCase, pNPCase, and pNPGase in the crude enzyme produced by the +VIB strain are 1.51, 41.10, 0.86, and 3.47 IU ml(-1), respectively, which increased 92, 34, 87, and 38% compared to the parent strain. Therefore, we believe that the VIB gene has an important effect on the cellulase of T. orientalis and overexpression of the VIB gene will increase the cellulase production. This study provided guidance for improving the cellulase production of T. orientalis.