Objective To evaluate the characteristic metabolic markers of the thymus metabolomics in DefensiveQi Deficiency syndrome and the intervention effect of Yupingfeng San. Methods Thirty SD rats were randomly divided into a normal group

a model group and a treatment group

with 10 in each. The normal group was fed normally. The model group was given fatigue combined with cold and heat alternating method to establish the DefensiveQi Deficiency syndrome model. The treatment group was gavaged with Yupingfeng San granules 25 g /（ kg·d） after the same daily modeling method as the model group for 7 days. The thymus metabolites were detected by High Performance Liquid Chromatography Mass Spectrometry（ HPLC-MC）

and the data were analyzed with principal component analysis（ PCA） and partial least squares discriminant analysis（ PLS-DA）. The primitive spectrum and data of thymus metabolomics of each group were compared with each other to determine the potential markers and their trends. Results Eight differential metabolites including cortisol

c AMP

thiamine

palmitic acid

homocarnosine

aspartyl threonine

dimethyl fumarate（ DMF） and adenine were the probable markers to distinguish the normal group from the model group. The palmitic acid level showed an upward trend in the model group

and the other seven showed a downward trend. The levels of 8 metabolites in the treatment group were turning normal as that in the normal group

with the palmitic acid level declined obviously and the others rose remarkably. Conclusion Cortisol

c AMP

thiamine

palmitic acid

homocarnosine

aspartyl threonine

DMF and adenine seem to be the characteristic markers of the thymus metabolomics in rat model of Defensive-Qi Deficiency syndrome

and Yupingfeng San could regulate back their metabolic disturbance in thymus.