Dark neck is firstly considered to be caused by excessive dirt or prolonged exposure to sunlight, resulting in melanin deposition. Secondly, consider the neck black due to acanthosis nigricans. Different causes correspond to different ways of improvement: 1, more dirt: if the neck black caused by untimely cleaning, can be carefully cleaned by using cleanser, bathing lotion, etc., to achieve the visual effect of whitening; 2, melanin deposition: if exposed to excessive exposure to ultraviolet rays in the sun, resulting in active melanocytes in the neck area, melanin deposition, there will also be the case of darkening of the skin at the neck. At this time, you can control the continued development by means of physical sun protection such as rubbing sunscreen on the neck, or carrying out physical sun protection such as foreign object shading. You can also use topical whitening products, such as foundation and concealer, to achieve a visual whitening effect. In addition, laser treatment can also achieve whitening effect, it is recommended to go to a professional hospital and follow medical advice; 3, acanthosis nigricans: it occurs in the neck, axillae, external genitalia and skin folds, initially manifested as pigmentation, dry and rough skin, small papillary elevation on the surface, and then papillomatous hyperplasia, lesions gray-brown or black. Topical vitamin A acid gel and cod liver oil ointment can be used. Patients with obesity need to reduce weight, and patients with drug-related acanthosis nigricans can get relief after stopping medication. In addition, malignant acanthosis nigricans requires identification and treatment of the malignancy, and visual whitening is usually possible only after the disease is cured.