YAlO3 single crystal doped with Ce3+ at concentration 1at% was grown by the temperature gradient technique (TGT). The as rown crystal was pink. After H2 annealing or O2 annealing at 1400℃, the crystal turned into colorless. At the same time, the absorption spectra showed obvious changes. A colorcenters model could successfully explain the experimental phenomena. There are selfabsorption and selfexcitation around 330 nm according to the absorption spectrum and luminescence spectra excited by ultraviolet ray. The emission peak of luminescence spectra under ultraviolet ray excitation is around 368 nm and the emission peak of luminescence spectra under x-ray excitation is around 391nm. These results suggest that the self-absorption can be decreased under x-ray excitation. In addition, the emission intensity of the crystals annealed in H2 or air is higher than that of the as-grown crystal sample.