To investigate the protective effect of maca polysaccharide(MP) on reproductive organs in aging model mice induced by D-galactose(D-gal).Methods:Fifty SPF male ICR mice were divided into a blank group，a model group，and low-，medium-，and high-dose MP groups by simple randomization according to the body weight，with 10 mice in each group.The mice，except for those in the blank group who received normal saline，underwent model induction by back neck injection of D-gal at 500 mg/kg every day for 8 consecutive weeks.The mice in the low-，medium-，and high-dose MP groups were given MP at 75，150，and 300 mg/kg daily by gavage for 8 consecutive weeks from the modeling.The morphology of mouse epididymis was observed with a transmission electron microscope，and the glutathione peroxidase(GSH-Px)，malondialdehyde(MDA)，and monoamine oxidase(MAO) activities in the testis tissues were measured.Real-time polymerase chain reaction(PCR) was used to detect the expression of superoxide dismutase 2(SOD2) and catalase(CAT) in the epididymis，and Western blot was used to detect the protein expression of silent information regulator 1(SIRT1) and P53 in the SIRT1/P53 signaling pathway.Results:After 48 days，the body weight growth of mice in each MP group was higher than that of the model group(P<0.05).The testis index and epididymis index of the medium-dose MP group were higher than those in the model group(P<0.05).Compared with the model group，the high-dose MP group showed potentiated GSH-Px activity in the testis tissues，decreased MDA content，and blunted MAO activity(P<0.05).The high-dose MP group had higher expression of SOD2 and CAT at the gene level than the model group.The expression of SIRT1 at the protein level in the testis tissues of each MP group significantly increased，and the expression of P53 at the protein level significantly decreased compared with that in the model group(P<0.05 or P<0.01).Conclusion:MP can protect the reproductive organs of mice by increasing the activity of GSH-Px and the expression of SOD2 and CAT at the gene level，reducing the activities of MDA and MAO，and regulating the SIRT1/P53 signaling pathway.