MgGa2O4:Mn2+ (MGM) and ZnGa 2O4:Mn2+ (ZGM) nanophosphors were synthesized in 1,4-butanediol by glycothermal method at 300°C for 2h. The optimum photoluminescence (PL) intensity of MGM at 0.5 mol% Mn is higher than that of ZGM at 3.0 mol% Mn. We discuss this reason from several points of view. Transmission electron microscopy reveals that the particle size of MGM is smaller than that of ZGM. The X-ray diffraction peaks of MGM are broader than those of ZGM. These results cannot explain the higher PL intensity of MGM. The electron paramagnetic resonance spectroscopy and the PL decay analysis reveal that the homogeneity of Mn2+ ions in MGM is higher than that of ZGM, resulting in the more efficient PL process for MGM. The high homogeneity of Mn2+ ions is possibly attributed to the formation of MGM from the low-crystallized glycoxide precursor with a homogeneous mixture of different metallic ions. In contrast, ZGM could be formed by the crystallization of ZnGa2O4, followed by the incorporation of Mn2+ ions into ZnGa2O4.