Using ultrasonic-assisted water extracted red bean polysaccharides as raw materials, response surface methodology was used to optimize the extraction process, and its antioxidant and antibacterial activities were evaluated. Response surface analysis results shown that the best extraction process for red bean polysaccharides is material-to-liquid ratio with 1∶26 (g/mL), ultrasonic temperature with 51 ℃, ultrasonic time with 94 min, the extraction rate of polysaccharide under these optical conditions is (9.92±0.04)%, which is basically consistent with the predicted value of the model. Red bean polysaccharides possesses strong total reducing ability and ability to remove ·OH and ABTS⁺·, and the removal ability has a dose-effect relationship with its concentration. In addition, red bean polysaccharides shown antibacterial activity against the four tested bacteria, especially for Staphylococcus aureus and Escherichia coli.