Aiming at the degradation of the output performance of optical fiber amplifier in irradiation environment, the photoannealing experiment of optical fiber amplifier after irradiation damage is carried out. Firstly, the influence of radiation on optical fiber amplifier is introduced. The irradiation experiment is carried out when the total irradiation dose is about 280 krad. It is known that the radiation will reduce the output power and optical signal-to-noise ratio by 7 dB and 18 dB respectively. Then, according to the mechanism of photoannealing, the photoannealing experiment of fiber amplifier is carried out. The experimental results show that the radiation-induced loss of the fiber amplifier is reduced by optical annealing. Compared with that before annealing, the output power of the amplifier is restored by 5.2 dB and the output OSNR is restored by 13 dB.