The synthesis and spectral properties of YAG:Tb phosphor were investigated. The results show that the single pure YAG:Tb phosphor powder can be synthesized at 1400 oC by solid state reaction. The Tb concentration has no influence on the excited spectra of the phosphor, while it changes the emission spectra and the relative brightness of the phosphor obviously. The relative brightness of the phosphor increases gradually with the growing Tb concentration. There is no obvious concentration quenching phenomenon in the experiment. The relative brightness of the phosphor increases first and then decreases with Ga doping. The excited spectra and emission spectra of the phosphor doped with Ga changes independently