Amorphous SiOx:C particles are prepared by pyrolyzing method, and then they are calcined in an air ambient at different temperatures. The structures mophologies and optical properties of samples are analyzed with FTIR spectrum, scanning electron microscopy and fluorescent microscope, respectively. The results show that the luminescence band is blue-shifted with the increase of the annealing temperature. The particles exhibit the highest photoluminescence intensity with the 417 nm peak when annealed at 500 ℃. And the particles possess red, green or blue light emissions at room temperature when irradiated with appropriate wavelengths. Upon heating at a higher temperature (600 ℃ or 800 ℃), the fluorescence intensity of the SiOx:C sample decreases. We think that the phenomenon is attributed to the reduction of the number of oxygen defects in the sample heated at high temperature.