Er3+/Yb3+Co-doped double-clad fiber amplifier pumped at 980 nm is analyzed for gain and noise characteristics based on the rate equation and light propagation equation. And the numerical simulation result shows that, under the conditions of both small and large signals, Er3+/Yb3+co-doped double-clad fiber amplifiers have good gains and noise characteristics within the range of 1520nm ~ 1570nm wavelength.