The dielectric confinement effect on the blue shift ΔEg(a) of the ZnO quantum dots (QDs) embedded in the SiO2 matrix is evaluated by applying a multi-shell two-electron system model. The experimental measurement and the calculations of various dielectric structures indicate that the composite matrix structure provides a better estimation of the blue shift of the ZnO QDs-SiO2 system than the multi-shell structure. The proportionality factor x defined in this work exhibits a dependence of the dielectric confinement energy on the specific dimension ratio (the b/a ratio) and the dielectric constant εmatrix of the outer matrix. The result of the calculation also shows the limit of the two-electron system in estimating the ground-state energy of samples with high dot density. However, the correlation shows the existence of the strong dielectric confinement effect in ZnO QDs-SiO2 thin films and allows a better understanding of the semiconductor QDs-dielectric systems.