In order to explore the antioxidant and hypolipidemic activities of flavonoids from seabuckthorn pomace extract in vitro， the antioxidant activity in vitro was evaluated by electron transfer mechanism (SET) and hydrogen atom transfer mechanism (HAT)， the in vitro test was used to simulate the gastrointestinal digestion environment of human body， and the hypolipidemic activity in vitro was evaluated by cholate binding capacity and cholesterol adsorption capacity. This study also compared the antioxidant and lipid-lowering activities of different polar extracts， and analyzed their chemical composition using high-performance liquid chromatography-mass spectrometry technology. The results showed the IC50 values of DPPH and ABTS free radical scavenging ability of flavonoids extract from seabuckthorn pomace were 30.491 μg/mL and 50.053 μg/mL. The IC50 values for the oxidation inhibition ability and phospholipid oxidation inhibition ability of linoleic acid extracted from seabuckthorn pomace flavonoids were 75.28 mg/mL and 66.16 mg/mL， respectively. The IC50 values of the flavonoid alcohol extract from seabuckthorn pomace for the binding ability of sodium taurocholate， sodium glycocholate， and sodium cholate were 3.09， 1.77 mg/mL， and 2.32 mg/mL， respectively. The IC50 values for cholesterol adsorption capacity under pH 2 and pH 7 conditions were 31.62 mg/mL and 9.69 mg/mL， respectively. The ethyl acetate extract had stronger DPPH radical scavenging ability and sodium glycocholate binding ability. A total of 18 flavonoids were identified in the ethyl acetate extract of seabuckthorn pomace， among which isorhamnetin， quercetin， and kaempferol had higher contents. The research results indicate that the in vitro antioxidant activity of seabuckthorn pomace flavonoids is mainly based on electron transfer， and the in vitro lipid-lowering activity is mainly based on the bile salt binding ability. The active substances are mainly concentrated in the medium polarity sites， with isorhamnetin being the most important flavonoid substance. This study provides a theoretical basis for the application of flavonoid extract from seabuckthorn pomace in natural antioxidants and auxiliary lipid-lowering health products.