The appearance of abdominal hair may be caused by genetic factors, excessive androgens in the body, endocrine diseases and other reasons. 1. Genetic factors: parents abdominal hair growth is more vigorous, may be passed on to the offspring through the gene, the offspring of the abdomen will also appear more vigorous hair. 2. Increased secretion of androgens in the body: the speed of physiological development increases after puberty, the level of secretion of androgens in the body increases, and the appearance of various sexual characteristics, which can cause abdominal hair. 3. Endocrine diseases: patients with endocrine diseases, such as Cushing’s syndrome, polycystic ovary syndrome and other diseases, the long-term use of adrenocorticotropic hormone, etc., will also induce abdominal hair. Long abdominal hair may be physiological phenomenon, may also be the cause of pathology, if there is an abnormal increase in hair, you need to go to the hospital in time for treatment.