Objective To explore the characteristics of magnetic resonance spectroscopy（MRS） of mild cognitive impairment（MCI） patients with liver-qi stagnation syndrome and the possible mechanism of treatment with Xiaoyao Pill（逍遥丸）. Methods Ten MCI patients with liver-qi stagnation syndrome formed treatment group

and another 10 healthy subjects with corresponding genders

ages

educational degree formed control group. The treatment group was given Xiaoyao Pill by oral administration

8 pills once

3 times a day in continuous 12 weeks

and no intervention in control group. Montreal cognitive assessment scale（Mo CA） was used to evaluate before and after the intervention of the treatment group and since inclusion starting for the control group. GE 3. 0 T super imaging system was used to detect the area under the curve of N-acetyla spartate（NAA）

choline（Ch）

myinositol（m I） of hippocampus

cingulate gyrus of left and right sides

and calculate the ratio to creatine（Cr）. Results Compared with the control group

the numerical value of nomenclature

abstraction

orientation in Mo CA of treatment group before intervention had no statistical significance（P > 0. 05）

and the scores of other items were significantly lower（P < 0. 05）.NAA/Cr in the left hippocampus was lower than the control group（P < 0. 05）. The numerical value of nomenclature

orientation in Mo CA of treatment group after intervention had no statistical significance when compare with before treatment（P > 0. 05）

and the scores of other items were significantly increased（P < 0. 05）. Ch/Cr in the right cingulate gyrus of MRS was lower than the control group（P < 0. 05）. Conclusion The decrease of NAA/Cr in the left hippocampus can be used as a marker of nerve injury in MCI patients with liver qi stagnation syndrome

and the decrease of the level of choline compound in the posterior cingulate gyrus of hippocampal loop may be one of the neurological mechanisms of Xiaoyao Pill to correct cognitive decline.