Hair loss on the top of the head may be related to normal physiological metabolism, may also be related to genetic factors, hormonal effects, immune abnormalities and other factors. 1. Physiological reasons: the human head hair follicles have normal cyclical changes, every day the human body hair will be normal shedding, if there is no obvious phenomenon of hair reduction, is a normal physiological phenomenon. 2. Pathologic causes: (1) genetic factors: if young people appear to head a lot of hair loss may be genetic factors, usually gathered in the family. (2) Hormone effect: when the body androgen too much, can prompt the hair follicle miniaturization, so that the growth phase of the hair can gradually become thin, shorten the hair growth cycle, caused by a large number of hair loss on the top of the head, often accompanied by the frontal hairline shifted back in the male. (3) Immune abnormalities: when the body’s immune mechanism is abnormal, such as baldness and other diseases, antibodies against the hair follicle’s own antigen may appear, leading to the loss of hair follicle function, resulting in hair loss on the top of the head. (4) Other factors: long-term mental stress, often late at night, nutritional imbalance can also induce a lot of hair loss on the top of the head, through relaxation, regular work and rest, adjust the diet can be relieved. It is recommended that patients with persistent hair loss on the top of the head go to the hospital in time to clarify the cause and follow the doctor’s instructions for standardized treatment.