Incarceration of prepuce is a common emergency in urinary system. When it happens, there will be local swelling of the foreskin and local pain in the glans penis. Long-term incarceration can lead to ischemia of the glans penis, which is manifested by local blackening, erosion and exudation of the glans penis, which is common in patients with phimosis and can also be seen in patients whose foreskin fails to recover in time after indwelling catheter. Acute pain will occur after sudden incarceration, which often belongs to emergency. The edema in the initial stage of incarceration is not particularly obvious, and the prepuce incarceration can be restored by manual reduction. The pain symptoms can disappear immediately after manual reduction of prepuce incarceration. However, if the incarceration time is long, it has caused ischemia and necrosis, or it cannot be manually reset due to local swelling, it needs immediate surgical treatment.