A kind of optical oxygen sensing material was obtained in a simple and low-cost method via assembling water-soluble silicon nanoparticles (Si NPs) into the well-ordered channel of SBA-15. The system we had developed showed high selectivity and sensitivity to oxygen which was attributed to large pore sizes and high surface-to volume ratios of SBA-15. The fluorescence intensities of the samples were recorded under different oxygen volume fractions. By analyzing experimental data, we found the samples had little response to carbon dioxide. The fluorescence intensity decreased prominently as oxygen volume fractions transformed from 0 to 100%. These results indicated that the SBA-15/Si NPs composites had superior properties for oxygen sensing and would provide broad application prospects in oxygen sensing or catalyst.