In most adult men, the length of the penis in the soft state is 3.5~10cm, and the length in the erect state is 1~2 times of the soft state, and the abnormal state needs appropriate treatment. The length of male penis is related to various factors such as ethnicity and individual differences. The length of normal adult male penis is 3.5~10cm when it is soft, and when it is fully erected, the length of penis can reach 1~2 times of the soft state. Normally, an erect penis of more than 7cm is normal and can meet the demands of a normal sex life. Some men with short penis usually have insufficient or abnormal secretion of sex hormones during the development process, thus the penis develops slowly or stops developing. In this case, supplementation of sex hormones can promote the development of the penis, and it is recommended that people with this condition undergo appropriate treatment according to the doctor’s diagnosis and treatment.