Blue phosphors Ca 1−x Al 2 O 4 : xEu 2+ were prepared by high temperature solid-state method. Their structure, morphology and luminescent properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and fluorescence spectroscopy. The effect of different amounts of fluxing agent H 3 BO 3 on structure, morphology and luminescent properties of blue phosphors Ca 1−x Al 2 O 4 : xEu 2+ luminous intensity caused by different amount of H 3 BO 3 was also investigated. The amount of H 3 BO 3 doped Ca 1−x Al 2 O 4 : xEu 2+ in optimal luminous intensity had been determined. The results showed that both the excitation and emission spectra of samples were all broad bands, and that the peak of emission spectra was near 442nm, which was corresponding to the 4f 6 5d→4f 7 transition of Eu 2+ illuminating blue light. Ca 1−x Al 2 O 4 : xEu 2+ (x=3.5mol%) could be gained with good morphology and the best luminous intensity when H 3 BO 3 mass ratio was 0.5wt%.