It is a kind of skin pigmentation disease, which is also called zygomatic nevus or zygomatic maternal spot because it occurs in the cheek area. The cause of formation is still unclear and may be related to genetic and embryonic development. During embryonic development, when melanocytes migrate from the neural crest to the epidermis, they fail to pass through the epidermis and dermis junction for some reasons and stay in the dermis. Later these immature dermal melanocytes are activated by ultraviolet light, radiation, hormones and their chemical factors and lead to the formation of lesions. After ultraviolet radiation, keratinocytes release endothelin 1 and granulocyte-macrophage colony stimulating factor, which can accelerate melanogenesis and thus aggravate the lesion. It has been pointed out that brown nevus has a certain degree of heredity, and the appearance of brown nevus can also be influenced by the external use of bad cosmetics and ultraviolet radiation. It has also been shown that cheek nevus may be related to abnormal androgen secretion. If grayish brown or dark gray pigmentation spots appear on the patient’s cheek, it is suggested to be a brown-cyanotic nevus, which needs to be diagnosed by histopathological examination. There is no effective drug treatment, but laser treatment can be carried out, which is characterized by less pain, faster effect and better prognosis. Patients should pay attention to keep facial skin clean in daily life, maintain a good state of mind and avoid low self-esteem, anxiety and depression due to brown nevus.