Dark spots on the face of over-obese people are usually caused by acanthosis nigricans. Its cause is not very clear at present, and it may be related to genetic, obesity, insulin resistance and other factors. Patients can be improved by weight control and medication. The clinical characteristics of acanthosis nigricans are mainly characterized by deepening of skin color and thickening of skin texture in a velvety manner. Its onset may be related to genetic or obesity factors, so the over-obese people may have black spots on their faces. For patients with acanthosis nigricans caused by obesity, the symptoms of acanthosis nigricans will be improved through proper weight control, exercise to lose weight, and oral hypoglycemic therapy for patients with insulin resistance. It can also be improved by using hydroquinone cream externally. For excessive obesity face with black spot patients, it is recommended to timely to the regular hospital for examination, under the guidance of professional doctors for standardized treatment.