For the space applications of high-power fiber lasers, we experimentally investigate the radiation performance of fiber lasers in radiation environment. The two fiber lasers, pumped at different wavelengths of 976 nm and 915 nm , are used with a same kind of 20/400 μm Yb-doped gain fiber in the experiment. After 12.4-krad irradiation by the γ ray produced by Co 60, the laser output powers of the 976-nm-pumped and 915-nm-pumped fiber lasers decay from 32.68 W and 32.04 W to 20.09 W and 5.63 W, respectively. The results show that the 976-nm-pumped fiber lasers are more radiation-resistant than the 915-nm-pumped fiber lasers. In addition, passive fiber devices, such as fiber combiners and cladding strippers, are used for irradiation experiments. After the irradiation, the coupling efficiency of fiber combiner is reduced, and the stripping degree of cladding stripper is increased. It is shown that irradiation has an effect on passive fiber devices.