Abstract: The water soluble polyester(WSP) was prepared by adding modifying components such as dimethyl terephthalate(TPA), dimethyl isophthalate(IPA),adipic acid(AA),dimethyl isophathalate-5-sulfonic sodium (SIPM),polyethylene glycol(PEG) and ethylene glycol(EG). The existence of SIPE is proved by the FTIR analysis. Tested the melting temperature, viscidity and other properties. And studied the crystallization capacity through DSC and X ray. Discussed the influences of chemical structure, temperature, surface area, surface active agent, electrolyte and pH value on the water solubility of copolyester. Then studied the solubility of WSP in the organic solvents. And also discussed the spinning ability of the water soluble polyester.