Objective：To investigate the current situation and characteristics of human immunodeficiency virus（HIV）/hepatitis B virus（HBV）co-infection among HIV-infected individuals，as well as to analyze the effectiveness of anti-retroviral therapy（ART）and its influencing factors for HIV/HBV co-infected patients. Methods：The study selected newly diagnosed HIV patients in Nantong City from January，2016，to December，2021，as the research subjects. Based on the results of hepatitis B surface antigen（HBsAg）testing， the patients were categorized into two groups：an HIV mono-infection group（1 830 cases）and an HIV/HBV co-infection group （135 cases）. The study compared the HIV infection characteristics of the two groups before ART，analyzed the virological suppression and CD4 ⁺ T lymphocyte count changes after ART therapy，and evaluated the improvement of immune function and its influencing factors. Results：HIV/HBV co-infection led to more severe immune impairment of the patients before ART than those in the HIV mono-infection group. After receiving ART，both the HIV mono-infection group and the HIV/HBV co-infection group showed a gradual increase in CD4 ⁺ T count，and the virological suppression rate was over 90% in both groups after two years of ART. Univariate and multivariate logistic regression analyses showed that the increasing age at ART initiation，initial CD4 ⁺ T count < 200 cells/μL，and initial HIV RNA ≥4.5［lg（copies/mL）］were risk factors for immune reconstitution. There was also an increasing trend in the rate of favorable immune reconstitution with a prolonged treatment time. Co-infection with HBV exacerbated immune impairment in HIV-infected individuals before ART，which may affect immune reconstitution. Conclusion：HBV infection can worsen immune damage in HIV-infected individuals. The current ART strategy for HIV/HBV co-infection effectively suppresses dual infection and benefits immune reconstitution in HIV/HBV co-infection. However，there are insufficiencies in ART and efficacy monitoring in patient management， highlighting the need for further standardization of clinical diagnosis and treatment activities.