Neutron-irradiation induced optical properties changes and defects formation in Ti-doped sapphire crystals were studied. Temperature gradient technique (TGT) grown Ti-doped sapphire crystals were irradiated by 1.5 MeV neutrons with a dose of 4.32×1016 neutrons/cm2. Absorption, emission and excitation spectra were presented. The 194-nm absorption band intensity enhanced and the 268-nm band weakened after irradiation. And the 420-nm luminescence band weakened and blue shifted to 414-nm. The results indicated that F+-type centers formed and the valence state of titanium switched from quadrivalent to trivalent during irradiation. Thermoluminescence (TL) was observed at 247℃ and assigned to irradiation-induced color centers. The thermoluminescence trap depth is 0.63 eV calculated with initial elevation method, and the lower thermoluminescence intensity is ascribed to the quenching effect of Ti ions.