The innate immune system is the first line of host defense against viruses. TypeⅠ interferons (IFNs)，the vital antiviral cytokines, play a critical role in establishing host antiviral state. Induction of typeⅠ IFN requires the formation of a multi-protein enhanceosome, including three families of key transcription factors (NF-κB, IRF3/7, and ATF-2/c-Jun). Transcription factor IRF3 (interferon regulatory factor 3) plays a pivotal role and is tightly regulated in this process. Recently, much progress has been made on cellular signal transduction and regulation of IRF3. Relevant advances in IRF3 biology were summarized with respect to its structure, function and regulatory mechanisms.