Rare earth ions' site occupation is significant for studying luminescence properties by changing the host composition. The (Ba1-xSrx)(9)Lu2Si6O24:Eu2+ (x=0-0.4) tunable-color phosphors were synthesized via a high temperature solid-state reaction. With the Sr2+ ions concentration increase, the luminescent color could be tuned from blue to green. This phenomenon is discussed in detail through the ions occupation in the host lattice. More importantly, the temperature-dependent luminescence of (Ba1-xSrx)(9)Lu2Si6O24:Eu2+ phosphors was investigated and exhibited excellent thermal stability. Furthermore, white LED device has been fabricated using (Ba1-xSrx)(9)Lu2Si6O24:Eu2+ phosphor mixed with commercial red phosphor Sr2Si5N8:Eu3+ combined with a 370nm UV-chip. This device showed correlated color temperature (CCT) of 5125K and high color render index (CRI) of 91. This phosphor will be a promising candidate as a tunable-color phosphor for UV-based white LEDs.