In this manuscript, a white-light emitting phosphor, Ca 8 MgLu(PO 4 ) 7 :Tm 3+ , Dy 3+ , with near ultraviolet excitation band and excellent thermal stability, is synthesized for the first time to the best of our knowledge. The energy transfer process of Tm 3+ →Dy 3+ has been investigated by the photoluminescence emission and excitation spectra, the decay curves. It is demonstrated that Tm 3+ can efficiently sensitize the luminescence of Dy 3+ under NUV excitation due to effective energy transfer from Tm 3+ to Dy 3+ , and the energy transfer efficiency can reach as much as 55%. The CIE coordinates of Ca 8 MgLu 0.76 (PO 4 ) 7 :0.12Tm 3+ ,0.12Dy 3+ phosphor are close to the standard values of National Television Standard Committee (NTSC) for white phosphor, which makes it be applicable to near ultraviolet based white light-emitting diodes.