Sulfonated-polyethersulfone/TiO2 (SPES/TiO2) nanoparticle composites with different TiO2 content were prepared by a sol-gel process. These composites have nanosized TiO2 rich domains well dispersed within SPES matrix observed by SEM photograph. The effect of TiO2 nanoparticles on the hydrophilicity of SPES was discussed by contact angle goniometer. The mechanism of the hydrophilicity improvement of these composites was analyzed by the molecular interaction theory and FT-IR. The hydrogen bond and coordination bond between SPES and TiO2 nanoparticle were observed. Comparing with the pure SPES, the SPES/TiO2 composites exhibited an outstanding increase in hydrophilicity.