The output power of a 1550 nm erbium-ytterbium co-doped fiber amplifier at different temperatures and the output power and spectra after high-temperature aging are experimentally studied. By comparing the output power of the amplifier varying with the pump power at high temperatures and normal temperatures, we verified that when the erbium-ytterbium co-doped fiber amplifier works in a high temperature environment, the output power can be increased. The sensitivity of gain fibers of different lengths to temperature is different. Using the Arrhenius model as the accelerated aging model, the accelerated aging experiment was performed on the gain fiber at a temperature of 85 ℃ for 876 h. The results show that the output power of the erbium-ytterbium co-doped fiber amplifier will be reduced by 11.24% after working in a normal temperature environment for 5 years. The amplified spontaneous emission noise will increase by 4.1 dB, and the service life of the amplifier is predicted to be 7.57 years according to the exponential model, which provides the theoretical basis and experimental basis for improving the output performance and life prediction of fiber amplifiers.