Abstract: The preparation of cold-water-soluble sweet potato starch was studied using alcohol-alkaline method, sweet potato starch as raw materials. The process conditions for preparing cold-water-soluble sweet potato starch were optimized. At same time,the viscosity property,retrogradation,and transparency of cold-water-soluble sweet were also determined. The results indicated that the best process conditions for preparing cold-water-soluble sweet potato starch were:amount of sodium hydroxide 30mL,volume concentration of ethanol 80% ,alkalization temperature 35℃ ,and ratio of solid to liquid 1∶5. Under the best conditions,the solubility of CWS sweet potato starch would reach 87.92%. The scanning electronic microscope revealed a lot of depressions and keyholes on the surface of CWS sweet potato starch particles,including the existence of adhesion of both, which made its great solubility and viscosity. What’s more,retrogradation,stability of the starch paste were all better than the original one. However,the transparency had been reduced.