Single phase of green-emitting X 2 –Y 2 SiO 5 :Tb 3+ phosphor was successfully prepared by a co-precipitation process at 1250°C. The photoluminescence of as-prepared X 2 –Y 1.9 Tb 0.1 SiO 5 was investigated in vacuum ultraviolet (VUV) region. The 141 and 170nm excitation bands were assigned to the charge transfer bands (CTB) of Tb (Y)–O and the absorption of SiO bonds, respectively. Under 147nm excitation, the phosphor showed main emission peak at 542nm attributed to the 5 D 4 → 7 F 5 transition of Tb 3+ , with an intensity of 176% of that of commercial Zn 2 SiO 4 :Mn 2+ and a 1/e decay time of 3.1ms, which was lower than the 5.1ms of Zn 2 SiO 4 :Mn 2+ .