Abstract: The polysaccharides structure and composition of fruit in three bitter melon inbred lines were compared in the paper. The crude polysaccharides were extracted in hot water and precipitated with alcohol. Then，the polysacchrides were purified by the processes of protein removing and dialysis. The polysaccharides composition and the types of its glycosidic bond were determined by gas chromatography and infrared spectroscopy respectively. The results showed that in the same growing environment，there are significant differences in the polysaccharide content，monosaccharide composition and the structure among different bitter melon inbreed lines. The water-soluble polysaccharide of bitter melon is mainly composed of arabinose，mannose，glucose and galactose，with the exception that inbreed lines of No.3 and No.8 contain small amount of rhamnose and xylose. In addition，configuration analysis showed the polysaccharides mainly exist in the forms of α- and β-pyranose in bitter melon.

Key words: bitter melon, bitter melon polysaccharide, monosaccharide composition, infrared spectroscopy, gas chromatography