Objective:To explore the neuroprotective mechanism of Zuogui Pills in Parkinson's disease（PD）mice based on the p53/p21 pathway.Methods:Sixty male C57BL/6 mice were randomly divided into a control group，model group，low-dose Zuogui Pills group（1.8 g·kg^-1·d^-1），medium-dose Zuogui Pills group（3.6 g·kg^-1·d^-1），high-dose Zuogui Pills group（7.2 g·kg^-1·d^-1），and Madopar group（50 mg·kg^-1·d^-1）using a random number table method.Except for the control group，all other groups were modeled by intraperitoneal injection with 1-methyl-4-phenyl-1，2，3，6-tetrahydropyridine（MPTP）（30 mg·kg^-1·d^-1）for five consecutive days.From the first day of modeling，the treatment groups were administered orally once daily for 10 days. Behavioral assessment，immunohistochemistry，Western Blot，ELISA，β-galactosidase（SA-β-gal）staining，and immunofluorescence staining were used to observe the effect of Zuogui Pills on cellular senescence in PD mice.Results:The open field test results showed that，compared with the control group，the total distance traveled by mice in the model group was reduced（P＜0.01）；compared with the model group，the total distance traveled by mice in the medium-dose and high-dose Zuogui Pill groups，as well as the Madopar group，was increased（P＜0.01）.The pole-climbing test results showed that，compared with the control group，the time for mice in the model group to climb the pole was prolonged（P＜0.05）；compared with the model group，the pole -climbing time was shortened in the high-dose Zuogui Pill group（P＜0.05）.Immunohistochemistry and Western Blot detection of tyrosine hydroxylase（TH）protein showed that，compared with the control group，TH protein expression in the model group was decreased（P＜0.01）；compared with the model group，TH protein expression was increased in the medium-dose and high-dose Zuogui Pill groups，as well as in the Madopar group（P＜0.05 or P＜0.01）.ELISA results showed that，compared with the control group，the levels of dopamine（DA），dihydroxy-phenyl acetic acid（DOPAC），and homovanillic acid（HVA）in the substantia nigra and striatum tissues of the model group were decreased（P＜0.01）；compared with the model group，the levels of DA，DOPAC，and HVA in the substantia nigra and striatum tissues were increased in the low-dose，medium-dose，and high-dose Zuogui Pill groups，as well as in the Madopar group（P＜0.05 or P＜0.01）.Immunofluorescence double staining results showed that compared with the control group，the number of Lamin B1（nuclear lamina protein B1）positive cells in the model group was reduced（P＜0.01），and the number of GFAP（glial fibrillary acidic protein）positive cells was increased（P＜0.01）. Compared with the model group，the numbers of Lamin B1 positive cells in the low-dose，medium-dose，and high-dose Zuogui pills groups，as well as in the Madopar group，were increased（P＜0.01），while the numbers of GFAP positive cells were decreased（P＜0.05 or P＜0.01）.Western blot results showed that compared with the control group，the protein levels of p53（tumor protein 53，TP53），CDKN1A（Cyclin-dependent kinase inhibitor 1A，p21），and CDKN2A（Cyclin-dependent kinase inhibitor 2A，p16）in the substantia nigra tissue of the model group were all elevated（P＜0.01）. Compared with the model group，the protein levels of p53，p21，and p16 in the substantia nigra tissue were reduced in the low-dose，medium-dose，and high-dose Zuogui pills groups，as well as in the Madopar group（P＜0.01）.SA-β-gal staining results showed that compared with the control group，the area of SA-β-gal positive expression in the substantia nigra tissue of the model group was increased（P＜0.01）；compared with the model group，the area of SA-β-gal positive expression was decreased in the medium-dose and high-dose Zuogui pills groups，as well as in the Madopar group（P＜0.05 or P＜0.01）.ELISA results showed that compared with the control group，the levels of IL-6 and IL-8 in the substantia nigra tissue of the model group were increased（P＜0.01）；compared with the model group，the levels of IL-6 and IL-8 in the substantia nigra tissue were reduced in the low-，medium-，and high-dose Zuogui Pill groups，as well as in the Madopar group（P＜0.05 or P＜0.01）. Conclusion:Zuogui Pill may exert a protective effect on PD model mice by alleviating cellular senescence through inhibition of the p53/p21 pathway.