Inclusion Criteria:  Patients diagnosed with urothelial carcinoma and undergoing immunotherapy ; Age ≥ 18 years; Expected survival time is greater than 12 weeks; Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 1 or 2;  Organ function level must meet the following requirements:  Hematological indexes: neutrophil count >= 1.5x10^9/L, platelet count >= 100x10^9/L, hemoglobin >= 9.0 g/dl (can be maintained by symptomatic treatment); Liver function: total bilirubin <=1.5 ULN, alanine aminotransferase and aspartate aminotransferase <=2.5 ULN (can be maintained by symptomatic treatment);  The subjects volunteered to join the study, signed informed consent, and had good compliance with follow-up; Willing and able to provide written informed consent.  Exclusion Criteria:  Receive live attenuated vaccine within 4 weeks before treatment or during the study period; Active, known or suspected autoimmune diseases; Cannot take orally or are allergic to probiotics ; History of primary immunodeficiency ; Known history of allogeneic organ transplantation and allogeneic hematopoietic stem cell transplantation; Pregnant or lactating female patients; Untreated acute or chronic active hepatitis B or hepatitis C infection. Under the condition of monitoring the virus copy number of patients receiving antiviral treatment, doctors can judge whether they are in line with the patients' individual conditions; Uncontrolled concurrent diseases, including but not limited to:  HIV infected (HIV antibody positive); Severe infection in active stage or poorly controlled; Evidence of serious or uncontrollable systemic diseases (such as severe mental, neurological, epilepsy or dementia, unstable or uncompensated respiratory, cardiovascular, liver or kidney diseases, uncontrolled hypertension [hypertension greater than or equal to conmon terminology criteria for adverse events （CTCAE） grade 2 after drug treatment]); Patients with active bleeding or new thrombotic disease.