Thinning hair in boys may be caused by genetic factors, seborrheic alopecia, seborrheic dermatitis and other factors. It is suggested to improve the bad habits, reduce the bad stimulation, give the right medicine can help improve. 1. Hereditary factors: If the grandparents or parents of the family have less hair and are affected by genetic factors, their offspring may have less hair. Hereditary factors cause hair thinning and usually cannot be changed. 2. Seborrheic alopecia: Seborrheic alopecia, also known as male pattern baldness, is characterized by increased sensitivity of the scalp to androgens, which inhibits hair growth. Minoxidil can be used externally to apply and Finasteride can be taken orally to reduce the destruction of hair follicles by androgens. Hair transplantation, if necessary, can improve the patient’s aesthetic appearance. 3. Seborrheic dermatitis: Seborrheic dermatitis is a common chronic inflammatory dermatosis, which may lead to erythema, follicular papules, flaking, and progressive hair loss on the scalp. It is recommended to ensure sufficient sleep, pay attention to balanced nutrition, correct skin care, and if necessary, give tretinoin and dexamethasone application to control inflammation. Those with fungal infection can be given miconazole, ketoconazole topical, and in severe cases, itraconazole and other oral medications. Hair thinning with flaking, greasy, hair loss and other manifestations can go to the hospital dermatology department, first to clarify the cause, and then targeted treatment.