The ZnO QDs/SiO2 composite materials,which were synthesized in different concentrations of SiO2-ethanol solution,were fabricated into light-emitting devices by spin coating.With the increase of SiO2 concentration,electroluminescence(EL) spectra of the devices are blue shift gradually.Experiments were designed and carried out to explore the mechanism of the spectrum-tunable EL with SiO2.The EL spectra of the series of devices,which were fabricated with the mixtures of the ZnO QDs/SiO2 sample and pure SiO2 in different molar ratios,indicate that the spectrum-tunable EL performance is not related to the emission of SiO2.The quantum size effect may be significant for the spectrum-tunable EL behavior,Gaussian multi-peak fitting for EL spectra showed that the increased ratio of green and orange-red emission with the increasing SiO2 concentration results in the blue shift of EL spectra.