Pentraxin 3 ( PTX3) is a soluble pattern recognition molecule, which can be rapidly produced by a variety of cells in response to inflammatory cytokines and microorganisms. PTX3 plays an important role in the innate immunity induced by bacterial, fungal, or viral infections. Recent studies have shown that PTX3 can bind to extrinsic antigens under inflammatory conditions, thus activating complement as well as promoting phagocytosis and other effector functions. In cancer, PTX3 activates and regulates the complement cascade by interacting with C1q and Factor H (FH), which can be used as an exogenous tumor suppressor to inhibit tumor-promoting inflammation. In damaged tissues, PTX3 can also play a role in tissue repair by combining with fibrin. As a result , PTX3 is a key component in resistance to infections, cancer, and tissue repair. In addition, PTX3 can also be used as a biomarker for a variety of human diseases, providing a new basis for clinical diagnosis. Based on the progress of research on PTX3, the article focuses on the function of PTX3 in different biological processes.