Micropenis is defined as a penis with normal appearance and normal length to diameter ratio, but the length of the penis body is less than 2.5 standard deviations or more from the average of normal penis length. The length of the penis is defined as the distance from the top of the penis to the pubic symphysis when the head of the penis is held as straight as possible, which is equivalent to a full erection. Adults are generally considered to have a small penis with a flaccid penis length of less than 3 cm. Congenital micropenis is very rare, is a kind of penile cavernous dysplasia malformation, penile body development is extremely poor, only the size of a soybean or green bean, more combined with hypospadias, is a clinical headache deformity. The majority of our common so-called small penis is occult penis or obese prepuce, not the real sense of small penis. Occult penis is a common congenital developmental abnormality and deformity. When a baby boy is born, the foreskin adheres to the glans of the penis body and the penis foreskin wraps around the penis head. By the age of 3-4, most children’s foreskin adhesions are absorbed and can be turned up on their own, with the penis head exposed. If at this time the foreskin still can not be turned up or the foreskin mouth is very small, it is called prepuce or prepuce. In the case of occult penis, the penis body is shrunken and hidden under the skin of the perineum, and only the small pointed foreskin protrudes outside, in the shape of a bird’s beak. If you squeeze the skin of the penis inward with your hand, the penis body will be revealed, but once you let go of your hand, the penis body will retract again. Therefore, some people call it a buried penis. The surgery of occult penis is not complicated, and the prognosis is good with very satisfactory surgical results. The key lies in correct diagnosis and differential diagnosis, once misdiagnosed, it will bring serious consequences, occult penis and circumcision and prepuce treatment can be said to be the opposite, circumcision and prepuce problem is that the foreskin long need foreskin removal, while occult prepuce is the outer plate of the foreskin is short, need to try to retain, the surgical method is completely different. The author has seen people misdiagnose occult prepuce as circumcision, resulting in a serious shortage of foreskin and an extremely troublesome secondary treatment. Many doctors confuse occult prepuce with obese prepuce, and the treatment results are naturally unsatisfactory. Obese prepuce is due to the accumulation of fat in the perineum caused by obesity, resulting in the penis body buried with subcutaneous fat. Some experts suggest that occult prepuce can heal itself after adulthood. Indeed, most adult occult prepuce can reveal the penis body and glans after erection, which does not affect sexual life. However, I have seen several cases of occult prepuce in adolescent children, where the penis body is completely normal after erection, but the penis body is still buried under the skin after erection disappears, and there is no penis body inside the foreskin, and the penis body often has more scrotal skin when erect, so such children are under great pressure in their minds, but it is much more difficult to correct at this time than in childhood. Therefore, severe occult prepuce must be operated.