Rare earth doped LaGaO3 phosphors could be suitable for use in field emission display and LED applications, owing to the excellent luminescent properties, high color rendition and stability, et al. The luminescent intensity and color purity of LaGaO3∶Tb3+ are higher than those of commercial Y2SiO5∶Ce3+ phosphor. In order to expand application in white LED, the luminescent intensity of LaGaO3∶Tb3+ is enhanced by co-doping Sn4+ ions in this paper. A series of green phosphor LaGaO3∶Tb3+ and LaGaO3∶Tb3+,Sn4+ were synthesized by high-temperature solid-state method. The crystal structures and luminescent properties were characterized by XRD and photoluminescence spectrum, respectively. The results show that all Tb3+ and Sn4+ ions preferably substitute for La3+ and Ga3+ ions, respectively, in the crystal lattice of LaGaO3 without impurity phases, indicating obtained samples are single phase phosphors. All excitation spectra consist of some broad peaks (231, 257, and 274 nm) and sharp peaks (from 300 to 500 nm). The bands at 231 and 274 nm are assigned to the spin allowed transition (LS, 7F6→7DJ, ΔS=0) and the spin forbidden transition (7F6→9DJ, ΔS=1) for 4f-5d of Tb3+, respectively. The band at 257 nm is assigned to the transition of a self-activated optical center related to octahedral coordinated GaO6 groups. Some excitation peaks in the range of 300～500 nm are attributed to f-f characteristic transitions of Tb3+, such as 7F6→5H6, 5H7, 5L6, 5L9, 5L10, 5G9 and 5D4. Compared with LaGaO3∶Tb3+, co-doped Sn4+ ion can enhance the 4f-4f characteristic excitation intensity of Tb3+. The main excitation peak changes from f-d transition of Tb3+ to its f-f transition. Under excitation at 308 nm, the emission spectra of LaGaO3∶Tb3+ and LaGaO3∶Tb3+,Sn4 all consist of Tb3+ ions characteristic transitions, such as 5D4→7F6 (487, 493 nm), 5D4→7F5 (545 nm), 5D4→7F4 (584, 589 nm), and 5D4→7F3 (622 nm). The strongest emission peak is at 545 nm. The CIE color coordinates of LaGaO3∶Tb3+ and LaGaO3∶Tb3+,Sn4+ are (0.287 4, 0.545 9) and (0.279 7, 0.576 1) in green region, respectively. The fluorescence lifetime of LaGaO3∶Tb3+ and LaGaO3∶Tb3+,Sn4+ are 1.63 and 1.38 ms, respectively； the color purity values of LaGaO3∶Tb3+ and LaGaO3∶Tb3+,Sn4+ are 54.81% and 62.67%, respectively. Co-doped Sn4+ ion has no impact on the position of emission peaks, but the emission intensity of Tb3+ increases to nearly double. Mechanism of concentration quenching can be changed from dipole-quadrupole (d-q) to quadrupole-quadrupole (q-q) interactions. The optimum doping concentration of Tb3+ is 0.05 and 0.07 in the LaGaO3∶Tb3+and LaGaO3∶Tb3+,Sn4+, respectively. The optimum Sn4+ doping concentration is 0.03. The optimum doping concentration of Tb3+ increases by co-doped Sn4+, which is beneficial to improving luminous intensity. The luminous efficacy values of the radiation (LER) of LaGaO3∶0.05Tb3+ and LaGaO3∶0.07Tb3+, 0.03Sn4+ are 464 and 485 lm·W-1, respectively. The internal quantum efficiency values of LaGaO3∶0.05Tb3+ and LaGaO3∶0.07Tb3+, 0∶03Sn4+ are 21.8% and 39.2%, respectively. The emission intensity decreases gradually with the increasing temperature due to the thermal quenching. The emission intensity of the LaGaO3∶Tb3+,Sn4+ sample remains to be above 70% at 150 ℃. According to the Arrhenius equation, the thermal activation energy ΔE for quenching is calculated to be 0.169 0 eV, which indicates that this phosphor has excellent thermal stability. All the results show that the LaGaO3∶Tb3+,Sn4+ phosphor is a promising green phosphor for the n-UV excited w-LEDs.