Under normal circumstances, the average length of an adult male penis when erect is 12cm to 14.5cm and the average circumference is 4.1cm to 5.2cm, but there are significant individualized differences. The length of the penis is measured when the penis is fully erect by holding it between the thumb and forefinger at the coronary groove and pressing the middle finger against the pubic symphysis, and the length measured is the erected length of the penis. If the length of the penis is less than 4cm when it is soft and less than 8cm when it is erect, it is called short penis, which belongs to a kind of underdevelopment, which is not conducive to the reproductive health of men and their normal sex life. Generally, it is caused by hormone level disorder, hypogonadism, androgen secretion abnormality, in addition, some obese men can also cause short penis. Male patients who have a short penis should go to the hospital in time for relevant examinations, and if necessary, they can use surgical methods to enlarge their penis, surgical risk selection should be careful. If the couple’s life is very harmonious, there is no need to care about the size of the penis, everyone’s excitement is not the same, penis length is only one aspect.