聚乳酸（PLA）作为一种具有良好生物降解性和生物相容性的聚合物，已经在航空航天、生物医学、食品包装等众多领域展示出应用潜力。然而，PLA也存在一些应用限制，如脆性大、强度低和降解速率慢等。为了克服这些限制并进一步改善PLA的性能，研究人员提出多种改性策略，其中包括添加纳米材料改性、添加生物降解材料改性、添加纤维材料改性、结晶度改性、增容改性、化学改性等。文章简要介绍PLA复合材料的结构及两种合成方法，系统综述上述改性技术的原理以及改性对复合材料在力学性能和结晶度的影响，最后对PLA复合材料改性技术未来的研究方向进行展望。

Polylactic acid (PLA), as a polymer with good biodegradability and biocompatibility, has shown extensive application potential in many fields such as aerospace, biomedical, food packaging, and so on. However, PLA also has some application limitations, such as high brittleness, low strength, and slow degradation rate. In order to overcome these limitations and further improve the performance of PLA, researchers have proposed various modification strategies, including adding nanomaterials for modification, adding biodegradable materials for modification, adding fiber materials for modification, crystallinity modification, compatibilization modification, functionalization modification, and copolymer grafting modification. The article briefly introduces the structure and two synthesis principles of polylactic acid (PLA) composite materials, and systematically reviews the principles of these modification methods and the effects of modified composite materials on mechanical properties and crystallinity. Finally, the future research directions of PLA composite material modification technology are prospected.