The structure of novel LiAlO2 crystal with Ti concentration of 0.2 at% was studied by measuring the absorption, luminescence and IR spectra. It was found that the crystal has the 196nm typical quarivalent Ti absorption peak, and also the 384nm typical quarivalent Ti emission peak when excited by 235nm light. A color-center model successfully explains the four small peaks in the range of 660—820nm, which disappeared when the samples were annealed in air or Li-rich atmosphere. Compared to the pure LiAlO2, we can find that the intensity and situation of ［LiO4］ are unchanged. Combined with the ICP results, we can count the number of Li vacancies to be about 5.5×1020 for the Ti: LiAlO2 with dimensions of 50mm×1mm.