To explore the renal protective effect and mechanism of mild moxibustion at Zusanli on naturally aging rats.Methods:Male SD rats were randomly divided into a natural aging group(n=10) and a moxibustion group(n=10) according to a random number table.Ten 9-month-old rats were assigned to the control group.The rats in the natural aging group were fed to the age of 20 months routinely.The rats in the moxibustion group underwent moxibustion at Zusanli from the age of 14 months，once a day for 20 min each time.The acupoints on both sides were selected alternately until the rats aged 20 months.Results:Compared with the control group，the natural aging group showed dry and yellow fur，low energy，stiff movement，altered renal structure，inflammatory cell infiltration and massive blue collagenous fibers in the renal interstitium，increased expression of β-galactosidase in renal tissues(P<0.05) and the content of 24-hour urinary protein(P<0.05)，and elevated mRNA expression of fibronectin(FN) and transforming growth factor(TGF)-β1 in renal tissues(P<0.01).Compared with the natural aging group，the moxibustion group showed glossy and yellowish fur，flexible and improved daily activity，reduced collagen staining，reduced expression of β-galactosidase(P<0.05) and the content of 24-hour urinary protein(P<0.05) in renal tissues，and declining mRNA expression of FN and TGF-β1 in renal tissues(P<0.05).Conclusion:Mild moxibustion at Zusanli can alleviate renal injury induced by aging，and has a protective effect on the kidney in naturally aging rats.The mechanism may be related to the inhibition of FN protein expression and TGF-β1 gene transcription in renal tissues.