Abstract: The American ginseng oligosaccharides (AGOS) were prepared by enzymatic hydrolysis of American ginseng polysaccharides (AGP). The antioxidant activity, in vitro hypoglycemic capacity and in vitro hypolipidemic capacity of AGP and AGOS were investigated by measuring their scavenging abilities on ABTS⁺, DPPH, OH, and O₂^-. The Fe²⁺ chelating capacity, total reducing power, α-glucosidase and α-amylase inhibiting ability, cholesterol binding capacity, sodium cholate binding capacity and lipase inhibition capacity were also measured. The results showed that the optimal conditions for enzymatic hydrolysis of American ginseng polysaccharides by cellulase were: Reaction temperature of 45 ℃, substrate concentration of 20 mg/mL, cellulase dosage of 100 U/mg, and enzymolysis time of 90 min. The average polymerization degree of AGP enzymatic hydrolysate under the condition was 2.74. American ginseng oligosaccharides showed better scavenging ability on ABTS⁺, DPPH and OH, and the scavenging rates were 74.63%, 79.98% and 99.94%, respectively, and had better inhibitory ability on α-glucosidase, α-amylase and lipase, the inhibition rates were 35.76%, 62.45% and 98.55%, respectively. The results would indicate that American ginseng oligosaccharide had stronger in vitro functional activity than American ginseng polysaccharide, and could be further developed and utilized as potential functional foods.