Abstract: Colloidal SiO₂ spheres were synthesized by hydrolysis of tetraethyl orthosilicate（TEOS） in the presence of water and ammonia in an alcoholic medium.In order to enhance surface charges of SiO₂ spheres,they were immersed into hydrogen peroxide solution（H₂O₂） for 48h at 30℃.SEM shows that the average size of SiO₂ colloidal spheres is 292nm,and its distribution standard deviation is less than 5%.FT-IR results indicate that hydroxyl group on the surface of SiO₂ spheres has increased through immersing them into H₂O₂ solution.Zeta potential of the treated SiO₂ spheres in water solution is improved from-55.72mV to-63.26mV,while surface charge density of the treated SiO₂ spheres is enhanced from 0.19μC/cm² to 0.28μC/cm².SiO₂ colloidal crystal was fabricated from aqueous colloidal solution by the vertical deposition method at 40℃ and 60% relative humidity,SEM images show that the sample of SiO₂ colloidal crystal is face-centered-cubic（fcc） structure with its（111） planes parallel to the substrate.Transmission measurement show the existence of photonic bad gaps,and the center of which is strongly determined by the incident angles.