The aim of this study is to investigate the prevalence and risk factors for hepatitis B virus (HBV) reactivation in HBsAg-negative/HBcAb-positive patients receiving immunosuppressive therapy for glomerulonephritis. We performed a retrospective study of 745 HBsAg-negative/HBcAb-positive patients undergoing immunosuppressive therapy for glomerulonephritis from years 2003 to 2012 at the department of nephrology, China-Japan Friendship Hospital, Beijing, China. The patients were divided into HBV reactivation group (n = 27) and non-HBV reactivation group (n = 718). The prevalence of HBV reactivation in patients receiving immunosuppressive therapy for glomerulonephritis was up to 3.62% in serological status of HBsAg-negative/HBcAb-positive. HBV reactivation was associated with several findings: greater proportion of lupus nephritis (25.93 vs. 9.61%, p = 0.014), much higher percentage of HBsAb-negative (74.07 vs. 23.82%, p < 0.001), longer duration of immunosuppressive treatment (100 vs. 70.06%, p < 0.001), as well as more cases of combined immunosuppressant (92.59 vs. 61.56%, p = 0.001). After univariate and multivariate analysis, three variables remained as independent risk factors for HBV reactivation: serological status of HBsAb-negative (OR 8.375, 95% CI 3.674-19.776, p = 0.001), length of immunosuppressive treatment more than 1 year (OR 1.308, 95% CI 1.121-1.358, p = 0.024), and combined immunosuppressant (OR 6.342, 95% CI 1.675-30.166, p = 0.003). HBV reactivation is not uncommon in HBsAg-negative/HBcAb-positive glomerulonephritis patients treated with immunosuppressant, and the prevalence was up to 3.62%. Patients with serological status of HBsAb-negative, more than 1 year of immunosuppressive therapy, and combined immunosuppressant are independent risk factors for HBV reactivation.