Abstract: Antimicrobials are indispensable drugs to inhibit bacterial infection. The overuse of conventional antibacterial (antibiotics) leads to the gradual enhancement of antimicrobial resistance of bacteria, which poses a serious threat to human health. As a new type of nano antibacterial material, carbon dots have the advantages of high anti antibacterial ability, wide range of raw materials, low cytotoxicity and good biocompatibility. Novel nano composite materials constructed by combining carbon dots with traditional antibacterial agents show great application prospects in the antibacterial field. This paper reviews the research progress on antibacterial mechanisms and applications of carbon dots and their composites. Firstly, the main factors affecting on the antibacterial performance of carbon dots are systematically analyzed by summarizing their antibacterial mechanisms. Secondly, the new nano composite materials combining carbon dots with traditional antibacterial agents and their applications in the antibacterial field are introduced. Finally, problems in the antibacterial application research of carbon dots and their composites are summarized and prospects are put forward, so as to provide reference experience for the design and synthesis of carbon dot composites with efficient and long-time antibacterial properties.