In this study, the effect of gamma-ray irradiation on the spectral and laser properties of Nd:GSAG crystal is investigated. With 20 Mrad gamma-ray irradiation, the crystal’s absorption at around 808 nm and emission at 1060 nm are only affected slightly. In addition, the lifetime of the 4F3/2 → 4I11/2 transition becomes longer when increasing the irradiation doses. All these optical properties changes after the irradiation could be attributed to the formation of F+-centers in the crystal. Using LD pumping, high-efficient 1.06 μm continuous-wave laser operation was realized in the crystal. It is worthy to note that the laser efficiency is influenced slightly by the gamma-ray irradiation, which suggest that Nd:GSAG crystal can be considered as a potential efficient laser gain medium for being used in radiant environment.