As a bio-stimulant with important clinical value, poly-L-lactic acid (PLLA) can speciffcally activate the proliferation and differentiation of dermal ffbroblasts and promote the synthesis and deposition of endogenous type Ⅰ and type Ⅲ collagen by precisely inducing controlled host cell responses. This process can not only restore structural volume, but also comprehensively improve skin thickness, elasticity and overall skin quality. Its clinical application has been successfully expanded from facial rejuvenation to body contouring. Compared with traditional ffllers, PLLA can provide more natural and longer-lasting regenerative effects. In addition, the physical properties of its microsphere suspension enhance application safety and reduce the risk of vascular embolism. This review aims to systematically collate and integrate the latest research evidence of PLLA in the ffeld of facial and body rejuvenation, analyze its biological mechanism, clinical application effect, safety and development prospects, so as to provide evidence-based guidance for clinical practice and theoretical support for the further development of this ffeld.