Abstract: Based on the theoretical model of Erbium-ytterbium doped fiber amplifier (EYDFA) and the analysis theory of stimulated Raman scattering effect, a hybrid amplifier structure combining EYDFA with second-order multi pump Raman fiber amplifier (RFA) was studied and designed by using the gain spectrum complementary characteristics of EYDFA and RFA. In order to obtain a hybrid amplifier with high gain and low flatness, a particle swarm optimization algorithm was introduced to optimize the pump wavelength and power. The simulation results show that, without the use of gain equalizer, the output power of the designed hybrid fiber amplifier is approximately equal, the average gain is 38.78 dB and the gain flatness is 1.1 dB in the bandwidth range of 90 nm, which provides a reference for the design and optimization of the hybrid amplifier.