To obtain more accurate optical properties, we optimize the oxygen vacancy in gamma-LiAlO2 with three different charges (0, +1, +2) to study the optical spectrum line shapes of the oxygen vacancy, and the defect formation energies are corrected by finite-size correction scheme (FNV). We obtain the optical spectra containing electron-phonon coupling. The absorption spectra of the F center and F+ center peak at 4.6 eV and 5.5 eV, which are close to the experimental result. So we predicate that the absorption band peak at 5.21 eV should be the origin of the F+ center. The luminescence peaks of the F center and F+ center are at 2.98 eV and 2.56 eV, respectively. Comparing with the experimental results, the emission peak (3.02 eV) is caused by the F center.