The foreskin is a normal tissue found on every man. In the past, it was commonly believed that the foreskin was just a folded skin tissue that did not serve any purpose. In particular, parents of boys lacked a proper understanding of the developing foreskin of their children and overly blindly took their children to the hospital for surgery. The foreskin of a man is no longer a superfluous “skin” tissue, but a “small organ” with special functions. So, what is the role of the foreskin? 1, protection function: foreskin covers the head of the penis to play a protective role. In infancy, the majority of foreskin and penis head is fused, wrapped around the entire head of the penis, only in the urethral location there is a narrow opening, can not stretch, flip, which helps prevent pathogenic microorganisms invasion. As we age, some cells in the area between the foreskin and the head of the penis gather into clusters, and the cells located in the center die due to lack of nutrition, forming a gap filled with dead cells, and several such gaps eventually fuse to form the space between the foreskin and the head of the penis, thus separating the foreskin from the head of the penis. This process of normal foreskin development helps to correctly recognize pediatric foreskin adhesions or prepuce and grasp the need for circumcision as well as the timing of surgery. In adulthood, the foreskin tissue is rich in muscle fibers and elastic fibers, so that the foreskin and the head of the penis can fit together well and play a protective role in covering the head of the penis, and also maintain the most ideal temperature, pH and clean environment. 2, immune function: foreskin immune system can prevent urinary tract infections. The mucous membrane on the inner surface of the foreskin contains a kind of immune cells, called Langerhans cells, which secrete cytokines that can kill pathogenic microorganisms. The squamous epithelial cells outside the foreskin can also secrete cytokines and interleukin-1, both of which can stimulate the immune response of the body’s T lymphocytes and improve the resistance of the urinary tract to disease. The moist environment between the foreskin and the head of the penis contains lysozyme, which can destroy harmful microorganisms, thus preventing urinary tract infections. 3, arousal function: foreskin is a normal sexual activity necessary to arouse erotic tissue. The structure of the foreskin and penis to feel external stimuli is called sensory receptors, there are two types of such structures, one is a special structure formed through evolution – mechanical receptors, can receive more accurate, subtle sensations; the other is a more primitive sensory tissue, that is, directly exposed nerve branch ends – -free nerve endings, feeling more primitive sensations. The foreskin contains a large number of mechanoreceptors. Recently, it has been discovered that the epithelial cells on the outside of the foreskin contain a special type of cell called a merkel cell, which is a tactile cell that senses external stimuli at the end of a nerve. These components are most abundantly distributed at the edges of the foreskin and can be well sensed for fine touch sensations. The head of the penis is mainly distributed by free nerve endings, with the most extensive distribution at the edge of the penis head, which can feel primitive pain sensations, warm and cold sensations and rough touch sensations. This distribution of sensory receptors in the foreskin and the head of the penis is complementary during sexual activity, and the complex interaction of the two is necessary for the process of arousal. Thus, it is clear that the foreskin is a useful tissue structure, which plays an important role in sexual life. A correct and objective understanding of the process of foreskin development, structural features and maintenance of the function of the foreskin can improve the quality of life of people.