Collagen/SiO2 composites were prepared in aqueous suspensions. Adsorption behaviors of collagen onto the surfaces of SiO2 spheres were studied. Structure and thermal properties were measured with FTIR, SEM, TEM and TGA-DTA. The results showed that the self-aggregation of collagen macromolecules was taken place during the adsorption of collagen on SiO2 sphere. The morphology of collagen evolved from line to microfibrils with the increase in the concentration of collagen along with the distortion of SiO2. Interfacial interactions of electrostatic forces and hydrogen bonding between the collagen macromolecule and SiO2 sphere had a vital effect on the adsorption of collagen. The amount of the collagen adsorption was increased with the increase of the collagen concentration, yet decreased in increased pH value of the solution. It was found that the composites exhibited lower infrared emissivity values in the wavelength ranged from 8 to 14 mu m than not only pure collagen but also SiO2 sphere, and the value of infrared emissivity was related to the adsorption amount of collagen in the composites.