A novel red emitting phosphor, Sm 3+ doped Mg 2 GeO 4 was prepared by the traditional solid state reaction. The luminescence properties were investigated in details. Diffuse reflection spectra of undoped and Sm 3+ doped Mg 2 GeO 4 were measured. The excitation spectra present a broad band and are consistent with the diffuse reflectance spectra. The emission bands which peak at 631 and 659nm are due to the 4 G 5/2 – 6 H 9/2 transition. The CIE coordinates of the phosphor Mg 2 GeO 4 :Sm 3+ is x=0.626 and y=0.323 which are close to the NTSC standard values for red. The dependence of the emission intensity on the Sm 3+ dopant concentration was studied: the optimum doping levels for Sm 3+ is x=0.03 molar ratio. The luminescence properties suggest it is a good novel red emitting phosphor.