In this work, we have investigated the effects of calcium on the atomic and electronic structures of CdSe quantum dots (QDs) by ab initio molecular dynamics. The increase in the CaO content in glass is found to break the linkage between Na and O atoms, while interactions between Cd atoms and nonbridging oxygen atoms are not disrupted. The presence of the CdSe QDs promotes the migration of Na atoms from the glass matrix to the interface and even the interior of CdSe QDs, while Ca atoms are only found to be present at the QD/glass interface and in glass matrices far from the QDs. However, on the basis of the radial concentration distribution, the CdSe QD only impacts the structure of glass at a short range near the interface. The increase in the CaO content is also shown to increase the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gap of CdSe QD-embedded glasses. Our findings can extend the understanding of the effects of calcium on the structural and luminescence properties of CdSe QD-embedded glasses.