Abstract: AIM: To study the characteristics of the four bioactive pure polysaccharides of Panax quiquefolium L. (PPQI 1～4). METHODS: The polysaccharides were extracted with hot water and grade precipitated with ethanol. They were further purified with Sephadex DEAE A50 and Sephadex G200 chromatography. The molecular weights of the polysaccharides were determined with matrix assisted laser desorption/ionization mass spectrometry (MALDI MS). The sugar compositions were analyzed with GC. The linkage positions of the component sugars were determined by methylation and GC MS. RESULTS: The four polysaccharides are all uronic acid containing heteropolysaccharides with the component sugars of arabinose, galactose and glucose in different molar ratios. The uronic acid contents are within 30%～60%. Their molecular weights are in the range of 2×10⁴～7×10⁴u. CONCLUSION: The four new bioactive polysaccharides are all uronic acid containing heteropolysaccharides.