HEC-g-AA/SiO2 hybrid materials are prepared through a graft copolymerization reaction between acrylic acid (AA) monomer and hydroxyethyl cellulose (HEC), in the presence of a silica sol. The microstructure and properties of the hybrid materials are characterized by Fourier transform infrared spectra (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively. The results show that a rigid inorganic phase SiO2 is dispersed in flexible organic continuous phase uniformly. HEC-g-AA/SiO2 hybrid material has no obvious phase separation in the presence of the crosslinking agent. The thermal performances of HEC-g-AA/SiO2 are excellent, and the glass transition temperature (T-g) increases with the increased amount of the crosslinking agent.