An S-band erbium-doped fiber (EDF) amplifier based on a W-type EDF designed by ourselves is demonstrated by employing a two-stage double-pass configuration.The amplifier provides a bandwidth of 34 nm (1486-1520 nm) for the gain over 20 dB.The maximal gain of 32.8 dB is achieved at 1501 nm and the corresponding noise figure is 6.0 dB.The proposed amplifier has a promising foreground in extending the current network to the S band.