Men’s neck black may be a normal physiological phenomenon, may also be due to acanthosis nigricans and other pathologic factors, need to clarify the cause of the disease, symptomatic treatment, common treatments are general skin care, medical treatment, medication, surgical treatment, and so on. 1. Physiological factors: long-term exposure of neck skin to ultraviolet radiation will make the melanin cells of the skin become active, resulting in darkening of the neck, which is a normal physiological phenomenon. It is recommended to pay attention to strict sunscreen, such as going out to apply sunscreen, playing umbrellas; you can also use skin care products with whitening effect; appropriate to eat more fresh fruits and vegetables; photorejuvenation and other treatments when necessary. 2. Acanthosis nigricans: it occurs in the neck, armpits and other skin folds, mainly characterized by excessive skin pigmentation and velvety thickening. Benign acanthosis nigricans can be improved by topical use of vitamin D3 derivatives, carboplatinol, salicylic acid and other keratinolytic agents; malignant acanthosis nigricans can be considered for surgical treatment. Boys with black neck may also be caused by other factors, such as eczema, dermatitis and other diseases can also lead to melanosis, it is recommended that boys with black neck seek medical attention in a timely manner in order to clarify the cause of the disease, targeted treatment, and avoid self-medication to avoid delaying the condition.