Background:Successful antiretroviral therapy (ART) has been demonstrated to be effective in reducing the infectivity of human immunodeficiency virus (HIV).We conducted a study to predict the potential effect of ART on the spread of HIV in Chaoyang District,Beijing,China,using the Asian Epidemic Model (AEM).Methods:The AEM baseline workbook was used to determine the current infection status and to project the future spread of HIV under current conditions.We changed the input on the ART coverage from 2014 to 2025 and also modified the treatment eligibility in the AEM intervention workbook,in order to allow for analysis of the projected downstream impact of ART.Results:By gradually increasing the ART coverage rate from 29.7％ (rate of 2013) to 40.0％,50.0％,60.0％,70.0％,80.0％,and 90.0％ (at CD4+ ≤350 cells/μl),and by changing the dates of coverage from 2014 to 2020,the number of new infections showed a cumulative decline of 0.60％,1.59％,2.94％,5.33％,9.32％,and 14.98％,respectively.After 2020,the projected rates of infection rebounded slightly,so with the exception of the years with very high coverage (90.0％),new infections continued to decrease.When we changed the initial threshold of therapy to CD4+ cell counts ≤500 cells/μl,new infections decreased 6.00％,11.64％,15.92％,2 1.11％,26.92％,33.05％,and 38.75％,respectively,under varying ART coverages.Conclusion:Our study demonstrates that the early initiation of ART for people living with HIV/acquired immune deficiency syndrome (AIDS) has a positive effect in slowing the spread of HIV.