After wavelength division multiplexing (WDM) optical fiber transmission system based on fiber Raman amplifier (FRA) is investigated in detail, the influence of the collocation of dispersion compensation fiber (DCF), the dispersion coefficient, dispersion slope (DS), effective core area, nonlinear index, length of FRA, launch power and the bandwidth of Bessel filter on bit error rate (BER) is deduced. The influence of Rayleigh backscattering noise on optical signal noise ratio (OSNR) is also investigated, which affects the performance of long haul transmission badly. The result indicates that the broadband long haul transmission can be realized through the reasonable design of the fiber. The result is useful to the optimaldesign of the WDM optical fiber transmission system based on FRA.