• All subjects voluntarily participated in the study and signed informed consent;

• Male or female aged ≥18 years and ≤75 years;

• Expected survival time ≥3 months;

• ECOG 0-1;

• Unresectable locally advanced or metastatic urothelial carcinoma confirmed by histopathology and/or cytology;

• Participants should not have received previous systemic therapy for locally advanced or metastatic urothelial cancer;

• A biopsy sample of archived tumor tissue or metastatic urothelial carcinoma must be available within 3 years for PD-L1 and other testing;

• At least one measurable lesion meeting the RECIST v1.1 definition was required;

• The level of organ function must meet the requirements on the premise that blood transfusion and the use of any cell growth factors and/or platelet-raising drugs are not allowed within 14 days before the first dose;

⁃ Previous treatment-related toxicity returned to ≤ grade 1 defined by NCI-CTCAE v5.0;

⁃ For premenopausal women with childbearing potential, a pregnancy test must be performed within 7 days before the initiation of treatment, the serum or urine pregnancy test must be negative, and the patient must not be lactating; All enrolled patients should take adequate barrier contraception during the entire treatment cycle and for 6 months after the end of treatment.