In this paper, aiming at practical dense wavelength division multiplexing (DWDM) system with ultra-long fiber span, a simple co-fiber remotely pumped erbium-doped fiber amplifier (RP-EDFA) scheme is proposed to extend span distance with simple configuration and low pump power. Equivalent noise figure of -6 dB is achieved under 300-mW pump power. Using the experiment results, numerical simulation of ultra-long span systems shows that for a 40*11.6-Gb/s transmission system, the RP-EDFA scheme can support transmission of 1760 km with a fiber span of 160 km. These results demonstrate the potential of the PR-EDFA scheme in ultra-long span transmission.