The authors prepared Na2SO4∶Eu, Gd, and Na2Gd2(SO4)4∶Eu phosphors by heating, the mixed powder of GdF3, EuF3 and natural mirabilite with muffle furnace at 1 000 ℃ for 30 min and continually heating it with microwave at 750 ℃ for 10 min. With increasing the concentrations of Gd ion, the 610 nm emission intensity due to Eu3+ was strengthened. Gd3+ probably formed a bridge between substrate and the activator so that the energy is able to be transferred efficiently. The luminescence intensity, along with colorimetric purity, reaches the top with 21 mol% Gd3+ doping in the thenardite (Na2SO4∶Eu) lattices, eventually coming up the quenching effects of concentration.