Lycium barbarum polysaccharides (LBPs) are the main active substances in Lycium barbarum L. for its ability to improve eyesight. This article constructs a new method for metal-free Fenton reaction degradation of LBPs, revealing the primary structure and eyesight-improving activity of LPBs with different components. A new method for degrading LBPs was constructed using an ultrasound-assisted H₂O₂/ascorbic acid degradation reaction, which established a metal-free Fenton reaction. This method was applied to degrade LBPs, which exhibit significant eyesight-improving activity. By adjusting the degradation time (0.5, 1, 3 h), three different degraded components of LBPs were prepared. Characterization of LBPs and its degradation products revealed that LBPs-3 had the low molecular weight and the highest content of arabinogalactans and uronic acids. Biological activity experiments indicated that LBPs-3 possessed the most potent eyesight-improving activity. The optimal LBPs component with the best eyesight-improving activity was screened, providing a theoretical basis for clarifying the pharmacodynamic substance basis of eyesight-improving activity of LBPs.