Objective To investigate the effect of poly-L-lactic acid (PLLA) combined with platelet-rich plasma (PRP) on volume enhancement rate and skin elasticity in patients with midface aging. Methods A total of 100 patients with facial aging who underwent facial contour reshaping and skin repair in Jinan Yestar Plastic Surgery Hospital from March 2023 to March 2024 were selected as the research subjects. According to the different treatment methods, they were divided into the control group (58 patients) and the experimental group (42 patients). The control group was treated with pure PLLA, and the experimental group was treated with PLLA combined with PRP. The facial volume enhancement rate, skin elasticity improvement rate, collagen content, patient satisfaction and adverse reaction rate were compared between the two groups. Results The facial volume enhancement rate of the experimental group was 85.71%, which was higher than 68.97% of the control group (P<0.05). The skin elasticity improvement rate of the experimental group was 90.48%, which was higher than 72.41% of the control group (P<0.05). The collagen content of the experimental group was (12.34±2.56)μg/mg, which was higher than (9.87±2.34)μg/mg of the control group (P<0.05). The patient satisfaction scores at 1, 3, and 6 months after treatment in the experimental group were higher than those in the control group (P <0.05). There was no significant difference in the incidence of adverse reactions between the two groups (P >0.05). Conclusion PLLA combined with PRP is beneficial to the improvement of facial volume enhancement rate, skin elasticity improvement rate and collagen content in midface aging, without increasing the incidence of adverse reactions.