Abstract: The extraction technology of polysaccharides from Leaves of Arctium lappa L. (i.e. PLA) was investigated with water extraction and alcohol sedimentation technique by single factor and orthogonal experiments. The antioxidant and antibacterial activities of deproteinized PLA were studied. The results showed that the optimum extraction parameters of PLA were material-liquid ratio of 1:30 (g:mL), extraction time of 2 h, extraction temperature of 75oC and extraction times of 2. PLA was purified by Sevag method, the analysis of UV spectrum showed that, no protein and nucleic acid existed in the purified product. And the deproteinized PLA was characterized by IR spectrum, which demonstrated that the product has the common spectral character of polysaccharides. The deproteiniezed PLA possess the scavenging capacity to hydroxyl radical and superoxide anion radical. And PLA has obvious inhibitory effect against Staphylococcus aureus, Escherichia coli and Bacillus subtilis.