Abstract: The purpose of this study was to find out the difference of monosaccharide composition and the antioxidative activity of polysaccharides obtained from thinned- young- apple and matured- apple pomace. The conventional hot water methods were adopted to extract polysaccharides from thinned- young- apple and matured- apple pomace. High performance liquid chromatography( HPLC) based on precolumn derivatization with PMP was employed to analyze the monosaccharide composition of both polysaccharides. In addition,the antioxidative activity of both polysaccharides were evaluated in vitro. The results indicated that both polysaccharides were composed of 10 kinds of monosaccharides,while the proportion of monosaccharides were different. The antioxidation experiments showed that two kinds of polysaccharides both had the reducing powers and the scavenging activity to · OH,DPPH· and O-2·.But the antioxidative activities of thinned- young- apple polysaccharides were higher than matured- apple pomace polysaccharides under the same concentration level.Thus,both the monosaccharides composition and antioxidant activity of polysaccharides from thinned- young-apple and matured- apple were different.