Objective To investigate the effect of poly-L-lactic acid (PLLA) combined with delicate pulsed light (DPL) on skin biophysical parameters in patients with facial photoaging. Methods A total of 100 patients with facial photoaging admitted to the Department of Cosmetic Dermatology, Nanjing Southeast Aesthetic Hospital from September 2024 to September 2025 were selected as the research subjects. According to the random number table method, they were divided into the control group and the observation group, with 50 patients in each group. The control group was treated with DPL, and the observation group was treated with PLLA combined with DPL. The overall facial photoaging, skin biophysical parameters, clinical efficacy and adverse reaction rate were compared between the two groups. Results At 6 months after treatment, the overall facial photoaging score of the observation group was lower than that of the control group (P <0.05). At 6 months after treatment, the skin elasticity parameter R2 and skin hydration level in the observation group were higher than those in the control group, and the melanin index and erythema index were lower than those in the control group (P <0.05). The total effective rate of the observation group (94.00%) was higher than that of the control group (80.00%) (P <0.05). There was no statistically significant difference in the incidence of adverse reactions between the two groups (P >0.05). Conclusion PLLA combined with DPL can effectively alleviate overall facial photoaging, improve skin elasticity and hydration, and reduce pigmentation and erythema. It has definite clinical efficacy, without increasing the incidence of adverse reactions.