Polysaccharides constitute approximately 8% of the dry weight of Pteridium aquilinum and are one of its primary active components.In order to investigate the effect of steam explosion processing on the saccharide of P. aquilinum,four dried  P. aquilinum samples from different origins were processed using the same steam explosion technique.After processing,the yield of total polysaccharide was determined.Using high performance liquid chromatography (HPLC) combined with 1-phenyl-3-methyl-5-pyrazolone (PMP) pre-column derivatization,a chromatographic fingerprint was established,and the common peak was confirmed with standards.Then the content of free monosaccharides and monosaccharide composition of polysaccharides were analyzed.At the same time,chemometric methods were used to evaluate the differences and similarities between samples.The results showed that compared with dried samples,the yield of total polysaccharides from steam-exploded samples was (12.02±1.89)%,an increase of 55% (P<0.01).There were 12 common peaks in the fingerprint of eight batches of P. aquilinum,and five common peaks were confirmed with standards,namely rhamnose,mannose,glucose,galactose,and arabinose.The results of hierarchical cluster analysis (HCA) and principal component analysis (PCA) can classify the eight batches of samples into two categories.The determination results of free monosaccharide content and polysaccharide monosaccharide composition showed that compared to dried samples,the content of free galactose,mannose and rhamnose in steam-exploded samples decreased by 6.02,0.42,and 0.34 mg/g respectively,while glucose and arabinose increased by 0.14 and 0.09 mg/g respectively;The proportion of glucose and rhamnose in the polysaccharide monosaccharide composition significantly (P<0.01) increased,with an average increase of 1.64% and 0.94%.This study found that the steam explosion process significantly increased the extraction rate of saccharide components in samples of P. aquilinum,and affected their content and structure.This serves as a foundation for future activity studies and offers a reference for quality control in steam explosion processing.