In this study, we evaluate three functionals (B3LYP, PBE, and M06) and 29 basis sets to find a suitable model to calculate silicon oxide clusters using density functional theory. The experimental values of electron affinities and vertical detachment energies of SiO2 and Si2O4 clusters were compared with the calculated ones using combinations of the three functionals and 29 basis sets. The calculated SiO bond lengths and SiOSi angles of Si2O7 cluster were also compared with the experimental values. Our conclusion is that the PBE/DGDZVP model is the best for calculating the structural and electronic properties of silicon oxide clusters.