A series of new green-emitting Ba2−x−2ySiO4:xEu2+, yGd3+, yR+ (R = Li, Na or K) phosphors were synthesized by the solid-reaction method. X-ray diffraction (XRD) and fluorescence spectrophotometer are utilized to characterize the crystal structure and luminescence properties of the as-synthesized phosphors, respectively. The XRD patterns reveal that the doping of Gd3+, Eu2+ and R+ ions have no significant influence on the Ba2SiO4 phase. The green emission of Eu2+ ion associated with 4f65d1 → 4f7 can be obtained by 396 nm UV excitation source, which match well with the emission wavelength of UV-LEDs chip (380–420 nm). Moreover, the effect of charge compensator ions (Li+, Na+ or K+) on the luminescence intensity of (Ba, Gd)2SiO4:Eu2+ phosphors were also investigated. When introducing the Li+ ions into the (Ba, Gd)2SiO4 host lattices, the as-prepared phosphors show the strongest emission. The emission intensity of Ba1.95SiO4:0.04Eu2+, 0.005Gd3+, 0.005Li+ is about 1.39 times than that of Ba1.96SiO4:0.04Eu2+. Furthermore, the mechanism of energy transfer and concentration quenching of Ba1.982−xSiO4:xEu2+, 0.009Gd3+, 0.009Li+ phosphors are also discussed.