Zero-phonon lines(ZPLs)associated with R_2 and N~- bands were observed in hydroxyl-doped sodium fluoride crystals irradiated by gamma rays at room temperature in the measured temperature range of 10-77 K.The N~- ZPL can be nearly completely bleached using normal spectrophotometer light at 10 K.An obvious spectral burning hole in absorption profile of the ZPL of the N~- color centers in the colored doped sodium fluoride crystals was obtained using the spectrophotometer light adjusted to narrower bandwidth at 10 K.Ultraviolet light radiation can mostly recovered the optical bleaching of the ZPL at proper temperature.Temperature dependence of spectral properties of 821 nm ZPL in the colored undoped sodium fluoride crystals were investigated at different temperatures.Value of Huang-Rhys factor of 2.49 was approximately estimated for transition of the color centers with 821 nm ZPL in the colored undoped sodium fluoride crystals.