Objective:To review the recent literatures related to the factors associated with the size of the HIV reservoir and their clinical significance.Data Sources:Literatures related to the size ofHIV DNA was collected from PubMed published from 1999 to June 2016.Study Selection:All relevant articles on the HIV DNA and reservoir were collected and reviewed,with no limitation of study design.Results:The composition and development of the HIV-1 DNA reservoir in either treated or untreated patients is determined by integrated mechanism comprising viral characteristics,immune system,and treatment strategies.The HIV DNA reservoir is a combination of latency and activity.The residual viremia from the stochastic activation of the reservoir acts as the fuse,continuing to stimulate the immune system to maintain the activated microenvironment for the rebound of competent virus once treatment with antiretroviral therapy is discontinued.Conclusion:The size of the HIV-1 DNA pool and its composition has great significance in clinical treatment and disease progression.