It is the most common cancer of the urinary system. Smoking is considered to be an important cause of cancer, with 50% of men and 31% of women with bladder cancer smoking. The carcinogenic quality is the presence of 1-naphthylamine and 2-naphthylamine in the urine of smokers. Occupational bladder cancer develops after years of exposure to benzidine and 2-naphthylamine, averaging about 20 years. Bladder cancer is the first tumor identified in humans with oncogenes, and deletion of the P53 anticancer gene on chromosome 17 is associated with the development. Bladder cancer can be divided into two categories: superficial and infiltrative: superficial tumors are confined to the mucosa without penetrating the lamina propria, accounting for about 80%. Infiltrating tumors invade the muscular layer, accounting for about 20%, of which some superficial tumors may develop into infiltrating tumors. The cell differentiation of bladder cancer varies greatly and has a close relationship with the prognosis. Intermittent and painless hematuria is the most common symptom of bladder cancer, which may delay the diagnosis due to intermittent and painless. There is no significant correlation between the amount of hematuria and the size, number and malignancy of the tumor. Hematuria may worsen eventually with bladder irritation symptoms. If there is putrid flesh in urine with difficulty in urination, most of them are advanced symptoms. Rhabdomyosarcoma of the bladder occurs in infants and children and presents mainly with dyspareunia and grape-like material in the urine. Urine cytology is extremely important and helps in diagnosis if tumor cells are found. Carcinoma in situ may be absent of hematuria but cancer cells are present in the urine. Cystoscopy is essential and plays a key role in deciding the treatment plan. Urography is mandatory for patients with bladder cancer to understand the kidneys and ureters. Flow cytometry and image analysis as well as tests such as ABO(H) and T antigen contribute to the understanding of the biological characteristics of the tumor. Carcinoma in situ and atypical proliferative lesions of the bladder mucosa are the basis for recurrence. In the treatment of superficial bladder cancer, in situ cancer is mainly treated by bladder perfusion, and BCG, mitomycin, adriamycin, thiotepa, interferon and interleukin are commonly used, with BCG having the best effect. Localized superficial bladder cancer can be treated by transurethral resection and postoperative bladder irrigation with the above drugs. In the absence of transurethral equipment, cystectomy or partial cystectomy can also be performed, but postoperative flushing with plenty of distilled water is necessary to prevent tumor implantation in the incision. Invasive bladder cancer is usually treated by radical total cystectomy with urinary diversion, except for very limited cases, which can be treated by partial cystectomy. Radiation and chemotherapy can sometimes be used in conjunction with surgery or as palliative treatment.