The penis is normally smooth, odorless, cylindrical, about 8 to 18 centimeters in length when erect, and sufficiently hard. The penis has the function of sexual intercourse, urination and ejaculation. It is divided into three parts: the head, the body and the root. The bulky front part is the head of the penis, the middle part is the body of the penis, which is cylindrical, and the back part is the root of the penis. The junction of the head and body is the coronal sulcus, and the tip of the head has the external urethral opening. The penis consists of two penile corpus cavernosum and one urethral corpus cavernosum, and the three corpus cavernosum are jointly wrapped by fascia and skin outside. The skin of the penis to the neck of the penis to form the penis wrapped around the head of the penis foreskin, the cavity between the foreskin and the head of the penis is called the circumcision cavity, the foreskin and the urethral opening connected to the folds of the skin, known as the foreskin tie. With age, the foreskin gradually retracts backward, and normally does not cover the urethra; if it covers the urethral opening, it is called phimosis. If there is any discomfort at the penis, it is recommended that the patient go to the regular hospital in time for treatment.