Innate immune system rapidly detects and responds to viruses at the early stage of viral infection. However, the mechanisms by which the immune system recognizes and eliminates them have not been fully clarified so far. Studies have shown that receptors are the primary tool for cell recognition and detection of viruses, and cyclic GMP-AMP synthase (cGAS) is one of the newly found DNA recognition receptors. cGAS transmits the signal to the downstream protein called STING (stimulator of interferon genes) and mediates the production of type I interferon (IFN-I), thereby to initiates the antiviral immunity of cells. This review briefly introduces the mechanism of the cGAS-STING signaling pathway, in order to provide a theoretical basis for the research and development of new antiviral drugs.