Abstract: Keratin is mainly present in the animal hairs, scales, feathers, hooves, horns and others, it is difficult to be degraded by conventional proteases due to its abundant disulfide bonds and hydrophobic amino acids, but keratinase can attack keratin more efficiently in the gentle conditions. Recently, the genetic engineering of keratinase had been developed to the stage of genetic modification, and the application of keratinase has also been gradually expanded. The origins, classification and properties of keratinase has been introduced by this paper. And the gene engineering of keratinase, mechanisms and applications were also reviewed, and it had provided a reference and direction for the further study of keratinase.