In radiation environments, the radiation induced attenuation (RIA) of the active optical fiber can lead to a significant decline in the performance of fiber laser system. An effective way to solve this problem is to bleach the active fiber using pumps at certain wavelengths, namely photo-bleaching. Experiments have shown that output power of irradiated Yb-doped fiber laser experiences remarkable recovery under 976-nm pump. However, under 976-nm pump, signals at both 976 nm and 1070 nm co-exist in Yb-doped fiber. Moreover, it is difficult to distinguish which wavelength is responsible for the photo-bleaching process. Herein, a one-hundred-watt level Yb-doped fiber laser is irradiated with gamma-ray radiation. In the radiation process, a significant output decline from 129 W at 0 Gy to 81 W at 100 Gy is observed. Then, self-bleaching test is conducted with 976-nm pump. After 2-h bleaching, the output power is restored to 111 W, corresponding to a recovery ratio of about 37.0%. To verify the specific wavelength responsible for the performance recovery, photo-bleaching characteristics of Yb-doped fiber lasers are investigated under different pump wavelengths including 915, 976, 1070 and 1550 nm. Experiments show that laser signal at 1 μm waveband is the primary cause for the bleaching of Yb-doped fibers, while, the pump at 915, 976 and 1550 nm can hardly bleach the irradiated Yb-doped fiber. The RIA recovery curves of Yb-doped fibers are measured under different 1070-nm bleaching powers. And, related evolution parameters are obtained through curve fitting. With these parameters, the RIA evolution of the Yb-doped fiber and the corresponding output power evolution of the Yb-doped fiber laser in the radiation and bleaching process are simulated. Comparisons show that the numerical results are consistent with the measurements qualitatively, demonstrating the reliability of the model. This work has guiding significance for predicting the performance of fiber laser systems in radiation and bleaching environments.