Red phosphors of Gd1-xAl3(BO3)4:Eux 3+ were synthesized by using the solid-state reaction method. The phase structure and morphology of the phosphors were measured using X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM), respectively. The optical properties of GdAl3(BO3)4:Eu3+ phosphors with concentrations of Eu3+ ions of 0, 0.05, 0.10, 0.15, and 0.20 mol were investigated at room temperature. The crystals were hexagonal with a rhombohedral lattice. The excitation spectra of all the phosphors, irrespective of the Eu3+ concentrations, were composed of a broad band centered at 265 nm and a narrow band having peak at 274 nm. As for the emission spectra, the peak wavelength was 613 nm under a 274 nm ultraviolet excitation. The intensity ratio of the red emission transition (5D0→ 7F2) to orange (5D0→ 7F1) shows that the Eu3+ ions occupy sites of no inversion symmetry in the host. In conclusion, the optimum doping concentration of Eu3+ ions for preparing GdAl3(BO3)4:Eu3+ phosphors was found to be 0.15 mol.