Facial melanin deposition is considered to be hyperpigmentation, and common causes include freckles, chloasma, Rheumatoid arthritis, and sunlight dermatosis. 1. Freckles: This disease is mainly related to autosomal dominant inheritance, and it occurs in the face, mainly in the nose and cheeks, with lesions of light brown to brown needle-tip to rice-grain sized spots, round, ovoid or slightly irregular, scattered distribution, and the color can deepen to black by ultraviolet irradiation. 2. Melasma: This disease is related to many factors, such as ultraviolet radiation, cosmetics, pregnancy, endocrine disorders, race, heredity, etc. It occurs in young and middle-aged women, and the lesions are often symmetrically distributed on the cheeks and cheeks of the face, which are in the form of butterfly-shaped, yellowish-brown or brown patches, and the color deepens after sun exposure to be brownish-brown. 3. Ruier melanosis: with the long-term use of cosmetics containing photosensitive substances, dietary deficiency of vitamin A, B, PP, and exposure to the sun can cause photosensitive dermatitis and lead to pigment metabolism disorders. It may also be related to gonadal, pituitary, adrenocortical and thyroid dysfunction. Manifested as mild itching of the skin, erythema after the occurrence of hyperpigmentation and other symptoms. 4. Sunlight dermatosis: this disease is mainly due to the skin received more than the amount of ultraviolet light tolerance, resulting in epidermal cell necrosis, the release of a variety of active mediators, causing dermal vasodilatation, tissue edema, melanin synthesis accelerated and other reactions, resulting in the face of the melanin pigmentation. It is recommended that patients go to the dermatology department of regular hospitals in a timely manner, follow the doctor’s instructions to clarify the cause of the disease, and timely treatment to avoid delaying the condition.