Small genitals in children can be caused by cryptogenic penis, penoscrotal fusion, circumcision scarring, small penis and other factors. 1. Cryptorchid penis: the appearance of the penis is small when there is cryptorchid penis, but when the penis is revealed after pushing the skin back, the size is usually normal, and the cavernous body of the penis is well developed, which is mainly due to the small opening of the foreskin, resulting in the glans not being able to be exposed, which leads to the appearance of small genitals. 2. Penile scrotal fusion: the lower part of the penis is fused with the scrotum on the ventral side of the penis, which leads to the appearance of a smaller penis, but when the penis is erected, the appearance can be normal. 3. Circumcision scarring: history of circumcision trauma or circumcision surgery can form localized scarring, resulting in the penis being constricted by the scarring and unable to extend fully, thus resulting in the appearance of a short penis. 4. Small penis: due to the hypothalamus-pituitary-gonadal axis and hormone synthesis and transformation process of the abnormal, resulting in the development of the penis is affected, the emergence of small penis, the penis is significantly smaller than the normal length, but also can be accompanied by sexual dysfunction, infertility and other symptoms. Children with small genitals should consult a doctor in time, under the guidance of a specialized doctor to actively carry out appropriate treatment, which will help to alleviate the uncomfortable symptoms as soon as possible.