Abstract: This study used kidney metabolomics to investigate the underlying mechanisms of Guilingji (GLJ) on mild cognitive impairment (MCI) rats. The rats were randomly divided into 6 groups (n = 8), i.e., control group, model group, positive drug (Ginkgo biloba tablet, donepezil) group, GLJ group (low and high dose group). The MCI rat model was replicated using subcutaneous injection of D-galactose into the back of the neck along with a semi-high-fat diet for a total of 8 weeks, and drug was administered from the 5th week for 4 weeks. The kidney function and renal pathological changes of each group of rats were tested. And LC-MS based kidney metabolomics coupled with multivariate data analysis were conducted to explore the potential biomarkers, and corresponding metabolic pathways were then determined. After administration of GLJ, the level of urea nitrogen was decreased compared with those of the model group, and the abnormalities of morphology in kidney tissues were improved. The positive drugs (ginkgo biloba tablet and donepezil) had no significant modulating effect on renal function indexes. Ginkgo biloba tablet can lessen the pathological injury of kidney tissue, and donepezil had no improvement on renal histopathology. A total of 23 MCI related differential metabolites were identified in kidney, and 17 metabolites were signifcantly restored by GLJ compared with those of the model group. Additionally, we found that the cysteine and methionine metabolism, nicotinate and nicotinamide metabolism, taurine and hypotaurine metabolism, glycerophospholipid metabolism were significantly involved in the regulatory effect of GLJ. The results illuminate the "cong shen zhi nao" mechanism of GLJ, and also provide a research basis for the clinical use of GLJ for the treatment of MCI. The animal experiment of this study was approved by the Ethics Committee of Shanxi University (approval number: 2020DW121).