Selenized Lonicera caerulea L. polysaccharide was obtained by microwave-assisted HNO₃-Na₂SeO₃ method and purified by column chromatography. The selenium content of the selenized polysaccharide was (0.184 ± 0.03) mg/g with an average molecular mass of 58828.3 kDa, and the polysaccharide was composed of galacturonic acid, rhamnose, arabinose, mannose, glucose and galactose with a molar ratio of 1:3.06:6.18:0.29:1.78:13.01. Nuclear magnetic resonance analysis showed six glycosidic bonds to be present in the selenized polysaccharide, namely →3)-β-D-galactose-(1→; →4)-β-D-mannose-(1→; →6)-α-D-glucose-(1→; →4)-α-D-galacturonic acid-(1→; →2,4)-α-L-rhamnose-(1→; and α-L-arabinose-(1→. The selenized polysaccharide at a concentration of 10.0 mg/mL reduced the oxidative hemolysis of erythrocytes induced by H₂O₂ by 32.52%, reactive oxygen species (ROS) level by 44.93%, and malondialdehyde (MDA) content by 17.04 nmol/mL, and decreased the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) by 163.93, 9.95 U/mg and 20.07 mU/mg protein, respectively. Therefore, the selenized polysaccharide from L. caerulea L. fruit can protect erythrocyte against oxidative damage.