The causes of long hair on the buttocks are physiological factors and disease factors (including polycystic ovary syndrome, drug factors, etc.). 1. Physiological factors: under normal circumstances, with the growth and development of the human body into puberty, the body’s hormone levels change, there will be secondary sexual characteristics, such as armpits, perineum, scrotum, anus and other parts of the long hair, the general growth of hair at the anus is shorter, is a normal physiological phenomenon. 2. Disease factors (1) Polycystic ovary syndrome: if female patients have more hair growth on the buttocks, then it is possible to suffer from polycystic ovary syndrome, which is related to heredity, environmental factors and other factors, and is manifested as menstrual disorders, infertility, hirsutism, thick pubic hair, spreading to the perianal area, groin or midline of the abdomen, and so on. (2) drug factors: if long-term local use of glucocorticoid drugs, etc., easy to trigger the side effects of long hair on the buttocks. It is recommended that patients according to their own situation, if necessary, to the regular hospital dermatology consultation, follow the doctor’s instructions to clarify the diagnosis, reasonable treatment.