Dermoscopy is a non-invasive technique developed in recent years to observe morphological features and digital image analysis on the surface of the body skin and the lower part of the epidermis that cannot be identified by the naked eye. Its characteristics are: non-invasive to the body, easy to operate, and a complementary diagnostic report can be given after on-site real-time examination. This technique is mainly applicable to the diagnosis of pigmented and non-pigmented skin lesions and their associated skin tumors, such as nevus cell nevus classification, pigmented nevus malignancy, malignant melanoma, basal cell carcinoma, squamous carcinoma, seborrheic keratosis, solar keratosis, Bowen’s disease, dermatofibroma, hemangioma and hemangioma-related birthmarks, and other pigmented lesions that are difficult to distinguish from melanoma, such as longitudinal black nail, subxiphoid nail The diagnosis and differential diagnosis of longitudinal black nail, subxiphoid hemorrhage, and black heel disease. In addition, the diagnosis of lichen planus, lichen planus, infectious molluscum contagiosum, mealybug, melanosis, psoriasis, dermatomyositis, purpura and leprosy vasculitis, especially for the early diagnosis of vitiligo is of great significance. In the past, most of these diseases were diagnosed by clinical eye or by surgical excision and pathological biopsy, although the diagnosis is reliable, it also increases the risk of trauma to the patient’s body and delays in treatment due to long diagnostic period. Dermoscopic image analysis technology can avoid these shortcomings and reduce the probability of trauma caused by surgical excision or biopsy, as well as effectively guide the scope of surgical excision, postoperative follow-up, selection of reasonable physical therapy and dynamic monitoring of lesions and suspicious lesions in high-risk groups, which are of great clinical importance.