We have demonstrated the blue and yellow electroluminescence of MOSLEDs made on Si-rich SiOx film with buried Si nanoclusters of different sizes. The situation of dehydrogenation of Si nanocrystals within the SiOx film becomes more pronounced then the re-growth of SiO2 matrix along with the prolongation of annealing time period. A linear variation on the O/Si composition ratio of the Si-rich SiOx film related to the deposition recipe is reported, giving rise to the precipitation of Si nanocrystals with different size. With such synthesis conditions, the SiOx films result in relatively strong photoluminescence at blue and yellow colors. From the comparison of the I–V curves we can conclude that there is a linear decrease on the threshold voltage of the SiOx based MOSLEDs by decreasing the thickness of the SiOx layer. According to EL pattern, we could demonstrate that the yellow- and blue-light pattern can be observed at 5.5 and 7.25 MV/cm, respectively.