Cavernous venous fistula, refers to an abnormality in the venous system of the cavernous body within the penis, where the venous return system is unable to close efficiently or the intracavernous pressure is lower than 80 mmHg, which leads to excessive venous return, causing insufficient or abnormal erection of the penis. It is usually caused by incomplete diastole of cavernous smooth muscle, loss of elasticity due to cavernous fibrosis, abnormal nerve control, and other pathologies such as malfunctioning of passive compression and closure mechanism of penile subxiphoid veins. The diagnosis of cavernous venous fistula is usually aided by tests such as nocturnal erectile function tests and penile cavernography. The main treatment modality is vein ligation surgery, which blocks the return of venous blood to the cavernous body of the penis to achieve effective penile erection. Prompt medical attention is recommended in case of discomfort.