A blue phosphor was obtained by doping Eu2+ into a multi-cation host Sr0.8Ca0.2Al2Si2O8 through high tempera-ture solid state reaction. The emission spectra show a continuous red-shift behavior from 413 nm to 435 nm with Eu2+concentration increasing. The substitution priority of Eu2+ in Sr0.8Ca0.2Al2Si2O8 was investigated via x-ray diffraction (XRD) and temperature properties in detail:the Ca2+ions are preferentially substituted by Eu2+at lower doping, and with the Eu2+concentration increasing, the probability of substitution for Sr2+is greater than that of replacing Ca2+. Accord-ingly, we propose the underlying method of thermal property to determine the substitution of Eu2+ in the multi-cation hosts. Moreover, the abnormal increase of emission intensity with increasing temperature was studied by the thermolumi-nescence spectra. The energy transfer mechanism between the Eu2+ions occupying different cation sites was studied by the lifetime decay curves. A series of warm white light emitting diodes were successfully fabricated using the blue phos-phors Sr0.8Ca0.2Al2Si2O8:Eu2+with commercial red phosphor (Ca Sr)SiAlN3:Eu2+and green phosphor (Y Lu)3Al5O12:Ce3+, and the luminescent efficiency can reach 45 lm/W.