Black petechiae on the tongue may be caused by physiological factors such as prolonged mental tension, late night, or moles, seborrheic keratosis and other conditions. 1. Physiological factors: usually for people who are in a state of long-term mental tension and patients with poor living habits and often stay up late, black ecchymosis on the tongue may occur, which is a normal physiological phenomenon. 2. Nevus: the cause of congenital nevus is still unclear, while acquired nevus is mostly considered to be related to trauma, drugs, hormone level changes and other factors. Patients often have spots or papules with clear boundaries, which can be brown or black, etc. If nevus pigmentosus appears on the tongue, black petechiae may appear on the tongue. 3. Seborrheic keratosis: It is usually considered to be caused by heredity, skin aging, gene mutation, etc. It is also related to tumors, drugs, ultraviolet radiation and other factors. Patients will appear round plaques, patches or papules, the surface is smooth or rough, the color can also gradually become black, which can also be manifested as black petechiae on the tongue. It is recommended that patients with black petechiae on the tongue actively cooperate with doctors to find out the cause of the disease and treat it reasonably.