The length of normal adult penis is around 13 centimeters when erect, and only 6 centimeters after erection is considered as small penis. The treatment of small penis is very difficult, including endocrine treatment and surgical treatment. 1. Endocrine treatment (1) For patients with abnormal pituitary function, human chorionic gonadotropin stimulation therapy, which is similar in efficacy to follicle stimulating hormone and luteinizing hormone. (2) For patients with abnormal hypothalamus function, direct replacement therapy with gonadotropin-releasing hormone should be applied. (3) For those with simple testicular function abnormality, testosterone can be used as a substitute, either topical testosterone cream or intramuscular testosterone injection. 2. Surgical treatment: testicular immobilization for patients with combined testicular descent insufficiency; for patients with buried penis, phalloplasty is needed. To summarize, patients with short penis should go to the hospital in time, and standardized treatment under the guidance of doctors.