Poly-L-lactic acid (PLLA) is a biodegradable polymer with good biocompatibility, which can promote collagen regeneration and skin repair. However, the research on the reaction mechanism caused by the injection of poly-L-lactic acid microspheres is still insufficient, and the research on PLLA is mostly in the direction of facial medical beauty. In this paper, the reaction mechanism and metabolic pathway of PLLA microspheres in regenerative medicine in aesthetic field were described. At the same time, the clinical application of PLLA in facial, neck, chest, buttocks, abdomen and limbs was reviewed. The adverse reactions after injection of PLLA were summarized, and a new direction for the development of PLLA in the field of medical aesthetics was proposed.