Abstract: The intestinal microbial community represents a highly complex ecosystem. Among the various bioactive molecules produced by microorganisms, the short-chain fatty acid propionic acid has garnered significant attention in recent years. It is primarily generated through the fermentation of dietary fiber by anaerobic bacteria in the colon. As a crucial mediator of host-microorganism interactions, propionic acid has been demonstrated to be extensively involved in multiple biological processes, including immune regulation, inflammation control, energy metabolism and neural signal transduction. This paper systematically reviews the biosynthetic pathway of propionic acid, with a focus on its core mechanisms in infection and immune regulation, its regulatory effects on diseases related to hospital-associated infections, its application potential for clinical infection prevention and control and its application prospects in microecological interventions. The aim is to comprehensively elucidate the mechanism of action and clinical value of propionic acid, providing new theoretical support for its clinical translational potential.