The broadband fiber Raman amplifiers pumped by multi-wavelength laser diodes are numerically simulated by using average power analysis method. A new method to optimize the pumping configuration efficiently is proposed based on the characteristics of multi-pumped Raman gain spectra and the fact that different pumps have different impacts on the gain slope. A fiber Raman amplifier pumped by 10-wavelength source is optimized and the gain ripple less than 0.5 dB in 70 nm gain spectra is obtained.