The upturning of the foreskin is usually caused by the excessive length of the foreskin and the foreskin is not reset in time. 1. Excessive foreskin: is the most common cause of foreskin upturning, in the penile erection, the glans is not exposed more than 2/3 of the position belongs to the foreskin, the foreskin is easy to lead to the foreskin upturning, premature ejaculation, impotence, sexual dysfunction, the existence of the foreskin scales, easy to induce bacterial infections, and so on. 2. The foreskin is not reset in time: cleaning or after sex the foreskin is turned out, not reset in time. After the discovery of the foreskin turned out must be timely reset, if found to form a certain degree of foreskin inlay, the formation of the inner plate of the foreskin redness, swelling, pain, etc., it is recommended to go to the hospital in a timely manner.