Abstract: A series of polyester resins were prepared by a melt polycondensation method using dimethyl5sodium sulfoisophthalate (SIPM), selfmade polyether polyol, dimethyl 2,6naphthalene dicarboxylate (NDC) and ethylene glycol as raw materials. The effect of SIPM content on the properties of resultant polyester resins was investigated, and the structure and physical and emulsifying properties of polyester resins were characterized by nuclear magnetic resonance, Fouriertransform infrared spectroscopy, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, Abbe refractometer and particle size analyzer. The results indicated that the glass transition temperature of the polyester resins increases with the increase of SIPM content. The polyester resins exhibited a high thermal stability, but their refractive index was reduced slightly from 1.606 3 to 1.600 4. The polyester resins could be easily emulsified by Tween80, and the lower the concentration of the emulsifier, the better the transmittance of the emulsions. The polyester aqueous emulsions showed excellent dispersion and stability after being stored for 100 days.