Poly (lactic-co-glycolic acid) (PLGA) is composed of lactic acid and glycolic acid monomers. It is the first biodegradable polymer to receive Food and Drug Administration (FDA) approval. PLGA is widely used in biology and medicine as a new delivery vector because of its structural adjustability, fast biodegradation rate and good biocompatibility. The modified PLGA nanoparticles (NPs) can effectively regulate drug release, enhance targeting, and greatly improve drug delivery efficiency, which has become a drug delivery vector with great potential in the biomedical field. This article comprehensively reviews the modification strategies of PLGA in recent years from two aspects, such as polymer (PEG, chitosan, etc.) modification and biomimetic cell membrane (such as cancer cell membrane, macrophage membrane, T cell membrane) modification, and its application in cancer immunotherapy. The immune mechanisms triggered by PLGA are also analyzed.At the same time, the limitations of PLGA NPs in clinical application and their wide application prospects in more fields in the future were proposed.