Inclusion Criteria:  Male ≥18 years and ≤75years of age; Confirmed diagnosis of hemophilia B (baseline FIX activity ≤ 2% of normal or documented history of FIX activity ≤2%); At least 100 days exposure history to FIX; Currently receiving FIX Prophylaxis therapy or on-demand treatment to prevent bleeding;  Have acceptable laboratory values:  Hemoglobin ≥110 g/L; Platelets ≥100×10'9 cells/L; AST, ALT, alkaline phosphatase ≤2×upper limit of normal (ULN) at the testing laboratory; Bilirubin ≤3× ULN ; Creatinine ≤1.5× ULN. No measurable factor IX inhibitor as assessed by the central laboratory and have no prior history of inhibitors to factor IX protein; Agree to use reliable barrier contraception until 3 consecutive samples are negative for vector sequences; Able to provide informed consent and comply with the requirements of the study.  Exclusion Criteria:  Have significant underlying liver disease within the past 6 months prior to or at Screening, including but not limited to:  Preexisting diagnosis of portal hypertension; Splenomegaly; Encephalopathy; Reduction of serum albumin; Evidence of significant liver fibrosis; Have anti-VGB-R04 neutralizing antibody titers ≥1:5; Evidence of severe infection disease, i.e., human immunodeficiency virus (HIV) infection, syphilis, tuberculosis, etc.; Evidence of active hepatitis B virus infection (HBV-DNA >103 IU/ml) or hepatitis C virus infection (HCV antigen and HCV-RNA positive); Evidence of malignant tumours or those with a previous history of malignant tumours; Have a history of chronic infection or other chronic diseases that the Investigator considers to constitute an unacceptable risk; Any immunodeficiency; Participated in a gene transfer trial within the last 52 weeks or in a clinical trial with an investigational drug within the last 4 weeks; Have used glucocorticoids, immunosuppressive drugs, or antipsychotics within the last 3 months; Previous history of hypersensitivity or allergic reaction to any FIX products or any immunoglobulin; Unable or unwilling to comply with the schedule of visits and study assessments described in the clinical protocol; Any concurrent clinically significant major disease or any other condition that, in the opinion of the Investigator, makes the subject unsuitable for participation in the study.