Abstract:As an Asteraceae herbaceous plant,dandelion （Taraxacum mongolicum） has been used as a food and medicine homology for many years. Rich in active ingredients including polyphenols and polysaccharides,dandelion has ideal antioxidant and antibacterial activities. In this study,the dandelion leaf and stem were selected as research objects. The dandelion polyphenol extract was prepared by ultrasonic-assisted ethanol-water extraction and phenolic compounds were identified by high pressure chromatography-mass spectrometry-mass spectrometry（HPLC-MS/MS）. Besides,polysaccharide extract was prepared by water extraction and alcohol precipitation and the monosaccharide composition in the polysaccharide extract was identified by HPLC. The results showed that the the dandelion leaf mainly contained caffeic acid（67.8 mg/g） while the dandelion stem mainly contained luteolin（89.3 mg/g）. D-mannose,D-rhamnose,D-glucuronic acid,D-galacturonic acid,Dglucose,D-galactose,and D-xylose were found in the leaf and stem polysaccharides. In monosaccharide content percentage from the stem polysaccharide extract,the top two monosaccharides were D-galacturonic acid（11.779%） and D-galactose （9.758%）. In contrast,the top two monosaccharides in the leaf polysaccharide extract were D-galactose （7.492%） and D-glucose （5.876%）,respectively. In addition,the dandelion stem polyphenol extract had a stronger ABTS+ free radical scavenging ability than leaf polyphenol extract,with halfmaximal inhibitory concentration （IC50） of 0.59 mg/mL and 0.76 mg/mL,respectively. Moreover,the dandelion stem polyphenol extract induced cell membrane rupture,exhibiting a notable inhibition effect on Staphylococcus epidermidis,with minimal inhibitory concentration of 0.95 mg/mL,but the leaf or stem polysaccharide extract did not show any inhibition effect.