The radiation experiment on the seed stage of narrow line-width fiber lasers by γ ray radiation with total dose of 50 krad(Si) is conducted. The output properties of this seed laser are analyzed before and after γ radiation. Experimental results reveal that the output power declines over 70%, and the temperature of gain fiber rises significantly as the loss increases. The radiated seed source is amplified to kW power level, presenting little change of output power, central wavelength, and 3 dB bandwidth at different radiation dose. However, the SRS suppression slightly decreased with the increase of radiation dose. 793 nm and 524 nm LDs with the same power are applied as bleaching sources of radiated seed stage, and the bleaching effect is analyzed. Due to higher photon energy and closer to the absorption peak of radiation-induced defects, 524 nm LD presents a better bleaching effect. The output power of seed stage and 793 nm bleaching duration presents a linear relationship with a bleaching speed at 0.30 W/h, and the output power and 524 nm bleaching duration approximately presents a tensile-exponential function relationship with a bleaching speed at 1.65 W/h.