KSr(Gd,Y)(PO4)(2): Tb3+ phosphors were synthesized using the high-temperature solid-state reaction method. The VUV-UV spectroscopic properties of these phosphors were studied. The results show that efficient energy transfer (ET) from Gd3+ to Tb3+ occurs in this system, and the ET efficiency increases with increasing of Tb3+ doping concentrations, which is evidenced that both the emission intensity and decay time of Gd3+ decreases with increasing Tb3+ doping concentrations. Visible quantum cutting via cross relaxation between the neighboring Tb3+ ions was observed in the high Tb3+ concentration doped sample. In addition, the emission color of KSr(Gd,Y)(PO4)(2): Tb3+ phosphors can be tuned from blue to yellowish-green by varying the doping concentration of Tb3+. Under 147nm excitation, the sample KSrGd0.5(PO4)(2): 0.5Tb(3+) exhibits the strongest emission, which is about 70% of the commercial green-emitting phosphor Zn2SiO4: Mn2+ indicating the potential application of this phosphor for plasma display panels, Hg-free lamps, and three-dimensional displays.