Abstract: The objective of this study was to optimise the extraction process of peptide of Poecilobdella manillensis by the Box-Behnken design-response surface methodology, and to investigate its whitening and anti-aging effects. Based on single factor experiments, NaCl solution concentration, extracting time and extracting times were taken as influencing factors, and peptide yield was used as the response value. The response surface model was designed and used to obtain the optimal extraction conditions of peptides of Poecilobdella manillensis: NaCl solution concentration of 4.3%, ultrasonic time of 4 h, and ultrasonic times of 2 times (2 + 2 h), which was significant and well-fitted to the actual experiment. The tyrosinase inhibition activity of peptide of Poecilobdella manillensis was evaluated by measuring the oxidation rate of levodopa (L-DOPA) catalyzed by tyrosinase. Moreover, using Caenorhabditis elegans as a model organism, the effects of peptide of Poecilobdella manillensis on body length, locomotion, reproductive capacity, reactive oxygen species (ROS), and lipofuscin levels were determined. The results showed that peptide of Poecilobdella manillensis exhibited a significant inhibitory effect on tyrosinase, with an IC₅₀ of 0.58 mg·mL^-1, which was stronger than that of the positive control arbutin (2.24 mg·mL^-1). Compared to the control group, 0.1, 0.5 and 1.0 mg·mL^-1 peptide of Poecilobdella manillensis showed no significant differences in the body length, eggs, and body bending of Caenorhabditis elegans. However, 0.5 mg·mL^-1 peptide of Poecilobdella manillensis significantly reduced ROS levels in Caenorhabditis elegans; 0.5 and 1.0 mg·mL^-1 peptide of Poecilobdella manillensis significantly reduced lipofuscin levels in Caenorhabditis elegans. Peptide of Poecilobdella manillensis exhibits effective whitening and anti-aging activities, potentially mediated by its inhibition of tyrosinase activity and antioxidant effects.