Bladder diverticulum is a hernia formed by the protrusion of the mucosa through the weak muscularis propria of the bladder wall. It can be divided into congenital and acquired. Most patients are asymptomatic, and be found by physical examination or incidentally during the diagnosis and treatment of other diseases. The majority of bladder diverticula occur in male patients, mostly due to lower urinary tract obstruction. Severe diverticula may cause recurrent urinary tract infection or even malignant transformation, which requiring surgical treatment.