In order to improve the amplification bandwidth of Raman Fiber Amplifier（RFA）and the transmission capacity of optical fiber communication systems

a broadband RFA with 100 nm bandwidth is designed by using four pumps with different wavelengths.Combined with the particle swarm optimization algorithm when solving the Raman coupled wave differential equation numerically

the wavelengths and powers of four pumps are optimized.The three sets of optimization results with average on-off gains of 18.690 9 dB

19.638 7 dB

21.764 1 dB respectively with corresponding gain flatness of 0.879 7 dB

0.914 4 dB

0.945 2 dB are obtained.Based on the three sets of optimized pump powers and pump wavelengths

the boundary conditions of particle swarm optimization algorithm are improved

which further improve the performance of RFA and particle swarm optimization algorithm.Finally

a broadband RFA with a gain of 22.480 4 dB and a gain flatness of 0.696 3 dB is realized.At the same time

the parameters of inertia weight and learning factors in the algorithm have been appropriately changed so as to analyze and compare how the optimization results change when different parameters are selected.The results of the analysis and comparison provide some references for the choice of algorithm parameters.