Penis size is mainly due to heredity, genes and other factors, the acquired may also be related to obesity, the body’s hormone secretion and other factors. Generally in China, the average length of adult male penis in soft and erect state is 8.1cm, 10.6cm, and the circumference of penis is 8.3cm, 12.1cm. The size of the penis is mainly due to heredity, genes, or with obesity, hormone secretion changes in the body, nutritional status and other factors. Pediatrics need to be compared with children of the same age group, if the penis of a full-term newborn pull length is greater than 1.9cm, it is a normal size. However, if the appearance of the penis is normal, but the length is less than 2.5 standard deviations from the average length of the same age group, the patient is a short penis. It may be caused by insufficient secretion of gonadotropins, excessive secretion of gonadotropins, androgen receptor abnormality, hypospadias, and other factors. Such patients may suffer from sexual dysfunction, infertility and other conditions, and need to take timely treatment measures. In daily life, men need to ensure sufficient rest time and do not overwork. If there is any discomfort, consult a doctor in time.