Objective: To investigate the duration of antibiotic therapy and its influencing factors in treating systemic lupus erythematosus (SLE) patients with community-acquired bacterial pneumonia (CABP). Methods: SLE patients with CABP were enrolled in this retrospective study from January 2012 to December 2018. The duration of antibiotic treatment (total, intravenous and oral) and its correlations with the severity of pneumonia and with the time to clinical stability (TCS) were analysed. A multivariate analysis was performed using a logistic regression model to determine the factors influencing the total antibiotic treatment course >10 d. Results: Two hundred seventy-six patients were finally enrolled in the study, and the mean duration of total antibiotic therapy was 14.6 days. The pneumonia severity index (PSI) was related to the total duration of therapy (r²=0.24, P<0.0001). The TCS was related to the total (r²=0.08, P<0.0001) and intravenous duration of antibiotic therapy (r²=0.69, P<0.0001). The CD4/CD8 ratio <1 (OR=4.911, 95% CI: 2.885–8.225), ICU admission (OR=3.501, 95% CI: 1.191–9.283), and double or triple antibiotic therapy (OR=4.911, 95% CI: 2.885–8.225) were the top three influencing factors (P<0.05, respectively). The optimum cut-off value for the PSI in predicting the total antibiotic therapy course >10 days was 139, yielding a sensitivity and a specificity of 73.33% and 74.07%, respectively. Conclusion: The duration of antibiotic therapy in hospitalised SLE patients with CABP was longer than the course recommended by practice guidelines. The severity of the disease and the host’s immune status might influence the duration of treatment.