The paper studied the hot water extraction of the water-solube polysaccharides from Dandelion, the content of polysaccharide is determined by phenol-sulphuric acid method.Result shows that the average content of polysaccharides from Dandelion roots,leaves and flowers are 56.02 %,16.50 %,36.24 %.The experimental result indicated all of the three organ polysaccharides have the effect of free radical scavenging.Roots polysaccharides have little effect of free radical scavenging than the leaves and flowers.Leaves and flower polysaccharides have great effect of scavenging for O2-·, the scavenging rate of which are 96.9 %, 96.6 %.Flower polysaccharides shows great effect of scavenging for ·OH, the scavenging rate of which is 70.3 %.The three organ polysaccharides have little effect of scavenging for LPO.The main finding is the leaves and flowers polysaccahrides have great effct of oxidation resistance.