In this paper, the performance of distributed Raman fiber amplifiers (DRA) with 40-channel wavelength division multiplexing (WDM) signals has been investigated. And the Raman fiber amplifiers with different pumping schemes and different fiber lengths have been reported. The gain and noise figures of the Raman fiber amplifier with 50 km of G.652 fiber have been compared at different pumping schemes. When the pump power and the signal power are not high enough, the Raman gain increases with the fiber length and the noise figure (NF) decreases with the fiber length. The optical signal to noise ration (OSNR) has also been investigated. It is found that the OSNR increases with the pump power, until saturated.