Abstract: Some LnBO₃: Ce³⁺(Ln=La,Gd or Y) phosphors were synthesized through solid state reaction. It was found that addition of NH₄X to LnBO₃:Ce³⁺ during firing increases the luminesence intensity of phosphors without changing the peak positions of excitation and emission spectra. As the radius of Ln³⁺ decreases and the crystal structure of LnBO₃:Ce³⁺ changes from orthorhombic to hexagonal, the peak position of excitation and emission spectra of LnBO₃: Ce³⁺ shift to longer wavelengths, showing an obvious influence of crystal-field on the 5d-4f transition of Ce³⁺.