Abstract: Polysaccharides were prepared from viscus of Patinopecten yessoensis,and the contents of neutral sugar,protein,sulfate,sulfated polysaccharides were determined as 75.37%,4.09%,0.63% and 8.77%,respectively,by chemical methods. IR spectrum showed characteristic absorption of polysaccharides. Acid hydrolysates of the polysaccharides from Patinopecten yessoensis viscus were analyzed by PMP-HPLC-PDA-MS.The results indicated that Xyl,Gal,Man,Rha,Fuc and Ara were the main components,whereas others,e.g.Glc N,Gal N,Gal A and Glc,were in a minor content.In addition,chondroitin sulfate or its analogue as well as three polysaccharides composed of a hexose and a hexuronic acid were found by analyzing the resulting disaccharides.This research provided information of polysaccharides in the scallop viscus,and helped to exploit and re-utilize this processing by-product.