Abstract: MicroRNA (miRNA) serves as a novel regulatory factor in viral and bacterial co-infections, exhibiting dual regulatory roles during pathogen infections. On the one hand, it exerts protective effects by modulating viral replication cycles and host anti-infection immune responses. On the other hand, it can be exploited by pathogens to promote infection progression, including influencing viral replication, antiviral immune responses, and regulating bacterial adhesion and proliferation. Mixed viral and bacterial infections lead to high mortality rates. By binding to specific target gene mRNA, miRNA degrades or inhibits its translation, thereby regulating target gene expression, which may ultimately serve as potential diagnostic and therapeutic targets. This paper reviews recent advances in research on the role of miRNA in viral and bacterial infections, particularly its mechanisms in co-infections, aiming to provide theoretical reference for further research on the infection mechanisms.