The new green-emitting phosphors Na 3 Y 1−x Si 3 O 9 :xTb 3+ (0.05≦×≦0.50) were developed by a solid-state reaction in this study. The excitation in VUV region showed a broad band in 150–180 nm with the strong absorption at around 149 and 178 nm, which are adjacent to the VUV excitation light sources of 147 and 172 nm. The composition of Na 3 Y 0.6 Si 3 O 9 :0.4Tb 3+ was observed to have the strongest emission around 541 nm. It showed the higher emission intensity, comparable brightness and a much shorter decay time under 147 nm excitation when compared with the commercial Zn 2 SiO 4 :Mn 2+ green phosphor. The results indicated that Na 3 YSi 3 O 9 :Tb 3+ could be potential candidate as a green-emitting VUV phosphor.