Abstract: Cucumber polysaccharides (CP) were obtained by hot water extraction, ethanol p recip itation, sevage method removing p roteins and organic solvent purification. Polysaccharides contentwas determined by anthrone - H2 SO4 colorimeter. Using the superox2 ide radical system , hydroxyl radical system , and system of 2, 2 - Diphenyl - 1 - p icryhydrazyl (DPPH·) , the antioxidation activities of cucumber polysaccharides is studied . The results showed that CP had strong radical scavenging activity towardsDPPH·, ·OH and O - 2 ·. The capacity of scavenging free radicals of cucumber polysaccharides showed linear connectionswith the concentration.