It is common to see parents bring their children who have just started kindergarten to the clinic because their penis is red, swollen, painful to urinate and even pus can be seen coming out of the foreskin. Parents are very nervous, and this is when we need to spread the knowledge of circumcision and prepuce to parents. We know that the foreskin is the layer of skin located at the front of the penis that wraps around the head of the penis, the glans. So what is circumcision and prepuce? In children, the foreskin wraps around the entire head of the penis, and as they grow older, the foreskin gradually recedes to the coronal sulcus of the penis, and if the head of the penis is still completely wrapped, it is called circumcision. If the foreskin is too long and the foreskin mouth is too narrow to flip behind the head of the penis, it is called prepuce. Next parents may ask: “Do all children with circumcision and prepuce need surgery? When is the best time to operate?” . Before answering this question, we need to understand the physical development of boys. According to statistics, 95% of boys’ genitalia begin to develop at the age of 9.5-13.5 years old, the testicles begin to increase in size around the age of 12, followed by an enlarged penis, loosened and colored scrotal skin, pubic hair and armpit hair, and the first seminal emission at the age of 14-15. It is normal for the foreskin to be too long in childhood, and as the penis grows older, the foreskin recedes backwards and the head of the penis is naturally exposed, so there is no need for circumcision at this time. Children congenital foreskin and glans adhesion, that is, congenital prepuce, also do not need premature surgery, this situation will be improved after a few years after birth, because with the growth of the penis, constantly pulling the foreskin, so that the foreskin mouth constantly expand, prepuce can become circumcised. For infants and young children with prepuce, circumcision expansion can be performed first to expand the foreskin, clean and reset it, and after repeatedly turning it over several times the prepuce can be transformed into prepuce. Surgery will be performed before puberty. In male adolescents, with the development of the penis, some of the prepuce can be transformed into prepuce or normal, but by the age of 14 this change basically stops. Therefore, in order to effectively prevent the complications of circumcision and prepuce, such as recurrent infections, premature ejaculation, non-ejaculation, and affecting the development of the glans, infants and young children can have their foreskin dilated and cleaned and often turned over for cleaning, and then circumcision can be performed after the appearance of the second sex characteristics before puberty. The best time to perform the operation is between 8 and 14 years old.