Objective To explore the clinical effect of cosmetic plastic surgery for senile lower eyelid relaxation. Methods A total of 47 patients with senile lower eyelid relaxation admitted to our hospital from July 2021 to October 2022 were selected as the research objects. They were divided into reference group (23 cases) and experimental group (24 cases) by random number table method. The reference group was treated with traditional cosmetic therapeutic apparatus, and the experimental group was treated with cosmetic plastic surgery. The psychological status, quality of life, improvement of lower eyelid relaxation and treatment satisfaction were compared between the two groups. Results The SAS score and SDS score of the experimental group were lower than those of the reference group, and the differences were statistically significant (P <0.05). After treatment, the scores of quality of life in the experimental group were higher than those in the reference group, and the differences were statistically significant (P <0.05). The improvement rate of lower eyelid relaxation in the experimental group was 95.83%, which was higher than 69.57% in the reference group (P <0.05). The treatment satisfaction of the experimental group was 91.67%, which was higher than 60.87% of the reference group (P <0.05). Conclusion Cosmetic plastic surgery has a good application effect in patients with senile lower eyelid relaxation, which can effectively improve the degree of lower eyelid relaxation and regulate the patient's bad mood, thereby improving their quality of life. Meanwhile, the patient's satisfaction with plastic surgery is high, which is worthy of clinical application.