• 1\. Male or female patients aged ≥18 year and ≤75 year

• 2\. According to the stipulations of Guidelines on Diagnosing \& Treating Bladder Cancer (Edition 2022) as promulgated by National Health Commission, an initial definite diagnosis of medium/high-risk non-muscle invasive urothelial bladder cancer (T1/Ta/Tis) as confirmed by histological examination and requiring an adjuvant therapy of BCG bladder instillation；

• 3\. After a thorough TURBt, all tumors should be grossly invisible. Patients requiring a second procedure are also eligible for inclusion. Those fulfilling the requirements of a second procedure may do so. Patients fulfilling the requirements of a second procedure shall meet the following criteria:

‣ Criteria of a second TURBt: 1) Initial TURBt is insufficient; 2) No muscular specimen during an initial TURBt; 3) Stage T1 tumor; 4) G3 (advanced grade) tumor, except for simple in situ tumor;

⁃ A second TURBt is recommended within Weeks 2-6 after an initial procedure. It is optimal at Week 4. After TURBt until BCG bladder instillation, no other instillations are allowed except for 1st/2nd immediate instillation chemotherapeutic agents. For the last TURBt, only epirubicin is reserved for immediate instillation chemotherapy;

⁃ Subjects undergoing a second TURBt and starting BCG therapy at Weeks 2-4 after a second procedure;

⁃ Based upon the first/second result of histopathology examination, comprehensively evaluating whether or not a certain patient is eligible for inclusion.

• 4\. A previous history of never receiving any therapy of BCG bladder instillation;

• 5\. ECOG score: 0-2 points;

• 6\. Clinical laboratory tests fulfilling the following features:

‣ Blood routine: Within Day 14 prior to randomization, never using any hematopoietic growth factor or blood transfusion, including absolute neutrophil count (ANC) ≥1500/mm3 or ≥1.5×109/L; platelet ≥100000/mm3 or 100×109/L; hemoglobin ≥9 g/dL.

⁃ Liver function: total serum bilirubin ≤1.5× upper limit of normal (ULN); for subjects with Gilbert syndrome total serum bilirubin \<3×ULN ;AST/ALT ≤2.5×ULN.

⁃ Renal function: defined as estimated creatinine clearance ≥50 mL/min according to the formula of Cockcroft-Gault;

⁃ Blood coagulation function: APTT ≤ 1.5×ULN and INR ≤1.5×ULN.

• 7\. Capable of understanding the procedures and methods of clinical study and participating voluntarily after offering thorough informed consents.