Gemcitabine (difluorocytidine) is a new cytosine derivative with the molecular formula 2,2,-difluorodeoxycytidine nucleoside. Gemcitabine is activated by deoxycytidine kinase after entering the body in order to act, forming gemcitabine phosphate (dFdCMP), gemcitabine diphosphate (dFdCDP) and gemcitabine triphosphate (dFdCTP), of which dFdCDP and dFdCTP are active products that can inhibit DNA synthesis. Therefore, this product is a pyrimidine cycle-specific antitumor drug, and its main metabolite participates in DNA intracellularly, acting mainly in the G1/S phase. A phase III randomized clinical study comparing GC and MVAC included 405 patients with advanced bladder cancer at 99 study centers. gemcitabine 1000 mg/m^2 was given on days 1, 8 and 15 in the GC group and cisplatin on the second day, repeated on day 28. The effective rates in both groups were 49% vs 46%, median TTP was 7.4 months in both groups, and median survival time was 13.8 months vs 14.8 months. the GC chemotherapy group had significantly less toxic side effects such as neutropenia, mucositis, and alopecia than the MVAC group. Therefore, it is considered as a new standard for the treatment of limited advanced and metastatic bladder cancer.