Analysis of polysaccharides and their hydrolyzed products in Cassia obtusifolia L.was performed by UV spectrometry and high performance liquid chromatography（HPLC），respectively.The composition characteristics of polysaccharides were developed,including 12 batches of Cassia obtusifolia L.The results showed that the content of polysaccharides extracted from samples were between 93.41% and 98.57% after purification.Under the optimized hydrolysis conditions，monosaccharides obtained were determined by HPLC with 1-phenyl-3-methyl-5-pyrazolone（PMP）derivatization.Based on HPLC data of 12 batches of samples，fingerprints of polysaccharides in Cassia obtusifolia L.were established.Common characteristic peaks were identified as mannose，glucuronic acid，galactosamine，glucose，galactose，xylose and arabinose，and their content was in the range of 1.617-304.5 mg/g.Polysaccharides for 12 batches of Cassia obtusifolia L.basically consisted of seven monosaccharides，named mannose，xylose，galactose，glucose，arabinose，glucuronic acid and galactosamine with an average molar ratio of 43.0∶24.2∶15.4∶5.6∶5.5∶3.4∶2.9.Fingerprints and molar ratio methods were successfully applied in the analysis of medicinal materials sold in market.