Abstract: Objective: The purpose of this study was to explore the protective effects of Polygonatum sibiricum extract (PSE) on the important organs of D-galactose (D-gal)-induced aging mice and its potential molecular mechanisms. Methods: The mice were randomly divided into five groups (n=10): control group, D-gal (500 mg/kg) group, low-PSE dose (0.5 g/kg) group, medium-PSE dose (1 g/kg) group, and high-PSE dose (2 g/kg) group. The organ indices (thymus, spleen, liver, and kidney) were detected. The levels of creatine kinase (CK), creatine kinase isoenzyme (CK-MB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), uric acid (UA), urea (UREA), creatinine (CREA), urea–creatinine ratio (BUN/Scr), and glomerular filtration rate (eGFR) in serum were measured. Pathological changes in the skin, liver, kidney, heart, brain, and lung of mice in different groups were analyzed by HE and Masson staining. The expressions of p53, p16, p21, RB, HO-1, Nrf2, and Keap1 mRNA in the liver, kidney, heart, and brain of each group of mice were detected by real-time PCR. Results: The thymus, spleen, liver, and kidney indices were increased in each PSE treatment group compared with those in the D-gal group (P<0.05). Moreover, in each treatment group, PSE decreased (P<0.05) the levels of CK, CK-MB, ALT, AST, ALP, UA, UREA, CREA, and BUN/Scr in mouse serum and increased the level of eGFR (P<0.05). HE and Masson staining showed that PSE could reduce the pathological damage caused by D-gal to the vital organs of mice. Compared with the blank group, the model group presented increased expression levels of p53, p16, p21, RB, and Keap1 mRNA in the liver, kidney, heart, and brain (P<0.05) and decreased HO-1 and Nrf2 mRNA (P<0.05). Compared with the D-gal group, mice in each PSE treatment group exhibited decreased mRNA levels of p53, p16, p21, RB, and Keap1 in the liver, kidney, heart, and brain tissues (P<0.05) and increased mRNA levels of HO-1 and Nrf2 (P<0.05). Conclusion: PSE has anti-aging effects, and its mechanism may be related to its inhibition of the p53/p21, p16-RB, and Keap1/Nrf2/HO-1 pathways.