Darkness under the eyes is usually caused by pigmented nevus, hemangioma and capillary dilatation, etc. Patients should go to the ophthalmology department of the hospital in a timely manner to diagnose the specific cause of the nevus. Nevus pigmentosus is usually caused by congenital developmental abnormality, and the affected area appears as a black patch with clearer boundary. If the pigmented nevus is on the lower eyelid of the patient, the patient may have darkness under the eyes. Hemangioma is caused by the proliferation of endothelial cells in blood vessels, and strawberry hemangioma and cavernous hemangioma are more common in clinic. Generally, when the patient is agitated or crying, the vascular expansion will be more obvious, which will make the black plaque darker in color and larger in area. Capillary dilatation is related to fatigue, late night and other reasons, if the patient eyelid subcutaneous rich capillary dilatation, blood stagnation, will cause the patient’s eyes localized darkening. It is recommended that patients with severe darkening of the eyes should seek timely medical attention to assess their condition and follow the doctor’s instructions for treatment.