Red-light emitting MgAl2O4:Eu3+ nanophosphors were synthesized by a micro-emulsion method. The photoluminescence properties of the phosphors with different Eu3+ ion concentrations (0–5 mol%) were investigated though excitation and emission spectroscopy at room temperature. The phosphors were further characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that pure MgAl2O4 spinels were synthesized at 1000 °C. The MgAl2O4 spinel crystallite size was observed under TEM about 10 nm at 1000 °C and 30 nm at 1200 °C, which was consistent with the size calculated by the Scherrer equation. The MgAl2O4:Eu3+ phosphors show typical red emission at 615 nm, which corresponds to the 5D0 → 7F2 transition.