The skin of the penis is thin, soft and stretchy, and the skin to the coronal sulcus of the penis head is free to form the foreskin of the penis. If the foreskin of adolescent men still completely cover the urethral orifice, you need to hand flip to reveal the urethral orifice and glans, for the foreskin is too long; if the foreskin mouth is too small, the foreskin is difficult to flip or simply can not flip, that is, the prepuce. Both of these conditions can easily lead to the accumulation of foreskin and foreskin scale, which can cause secondary infection and inflammation of foreskin and penis, and if not taken seriously, long-term chronic stimulation can lead to penile cancer. Penile cancer mostly occurs in middle-aged men. In the early stage, small papules or small ulcers appear on the head of penis, and later become larger ulcers. Since the foreskin is not easily turned up, the lesion is not easily detected and only feels some tingling and burning pain. With the development of the disease, the lesion will gradually grow into a large ulcer and protrude to the surface of the penis, forming an ulcerated penile head or cauliflower-shaped lump with pus and blood discharge and bad odor, and the cancer cells will quickly metastasize to the adjacent lymph nodes or distant parts of the body. The most common type of penis is penile head infection or prepuce, which is characterized by local tissue erosion, redness, swelling and pain, and a little purulent discharge, which can be controlled by timely treatment; secondly, penile head allergy, which is mostly seen in condom allergy, with penile head erosion, oozing, tingling and scratching. Systemic and local drug allergies can sometimes manifest as priapism or prepuceitis. In addition, there are sexually transmitted diseases such as syphilis that can also cause penile ulcers. All these diseases can be controlled with treatment, but the ulcers of penile cancer are indifferent to all kinds of drugs. Therefore, once a long-lasting ulcer appears on the penis, we should be alert to penile cancer.