In this paper, to compare the antidiabetic effects of crude polysaccharide of Iron Stick Yam and Bergamot Yam, the scavenging effect of crude polysaccharide of the two yams on DPPH and PTIO free radicals, the inhibitory effect on α-glucosidase, and the hypoglycemic and hypolipidemic effect were determined. A type 2 diabetes model was established and metformin was used as the positive control drug. The EC50 (μg/mL) of the two yam crude polysaccharides were 35.38 and 16.19 for DPPH radical scavenging (p<0.01) and 7869.17 and 8335.78 for PTIO radical scavenging (p<0.01), respectively, and the inhibition of α-glucosidase (18.85% and 15.73%) were not significantly different (p>0.05). Compared with the model group, FBG, TC, and LDL-C levels were decreased by 24.38%, 28.44%, and 44.68% (p<0.05, p<0.01), liver glycogen content was increased by 21.83% (p<0.05), and CAT and GSH-Px levels were increased by 363.36% and 43.67% (p<0.01) in the Fructus yam crude polysaccharide group. FBG, TG, TC, and LDL-C levels decreased by 25.62%, 28.52%, 22.79%, and 44.73% (p<0.05, p<0.01), and SOD and CAT levels increased by 7.22% and 69.76% (p<0.05), respectively, in the Fructus yam crude polysaccharide group. The results indicated that the two crude polysaccharides had different mechanisms of antidiabetic effects. The crude polysaccharide of iron stick yam was more advantageous in scavenging PTIO radicals, reducing hepatic glycogenolysis, and enhancing CAT and GSH-Px activities, while the crude polysaccharide of Buddha's hand yam was more effective in scavenging DPPH radicals, reducing TG content, and enhancing SOD and CAT activities.