Cathepsins (Cat) are the main members of the cysteine protease family, and relate closely to some dermatosis, for example, cutaneous tumor, chronic inflammation. Many recent investigations manifest cathepsin’s significance in skin physiology as followed: CatD/CatL/CatV maintain normal epidermal differentiation and intact barrier; CatB/CatD/CatG/CatK keep the homeostasis of extracellular matrix (ECM); CatV insure of normal development and growth cycle of hair follicle. Those studies have been deepen in cell signals and gene regulations, and increased the understanding about the regulation of normal skin physiology. It’s also possible to apply to the gene therapy field in the future.