An efficient short wavelength band erbium-doped fiber amplifier (S-band EDFA) is proposed and demonstrated using double-pass configuration. This amplifier provides a gain as high as 30dB, but using only 15m depressed cladding erbium-doped fiber (EDF) and 130mW of 980nm pump power. Compared to the single-pass configuration, this amplifier shows a gain enhancement of about 14dB for pump powers above 120mW. However, noise figures penalties of about 0.5 ∼ 0.9dB are obtained for these pump powers. The proposed double-pass amplifier will play an important role in the development of a practical S-band EDFA from perspective of economical usage of EDF and pump power.