Pump-signal four wave mixing(FWM)in co-pumped distributed Raman amplifier(DRA)is studied. Also,the calculation formula for the FWM power in DRA with nonuniform zero dispersion wavelengths is derived based on the method of sum of subsections. FWM induced channel crosstalk distribution along the transmission fiber and the interrelationship between FWM and the location of the fiber zero dispersion wavelength are simulated numerically. The suppression effect on FWM by introducing proper dispersion compensation fiber(DCF)is analyzed theoretically. Computational results show that,strong pump-signal FWM effect occurs in DRA with nonzero dispersion shifted fiber(NZDSF)as gain medium,which seriously degrades transmission performance of the dense wavelength division multiplexing(DWDM)system. Introductionm of appropriate DCF can not only reduce FWM channel crosstalk but also eliminate the waveform distortion induced by dispersion effectively.