We demonstrate the all-fiber picosecond erbium-doped fiber lasers in which graphene oxide is used as the saturable absorber. The linear resonant cavity consists of a narrow band fiber Bragg grating and a graphene oxide saturable absorber mirror. When stable mode-locked pulses of the fiber laser occur at 22 mW incident pump power, the pulse repetition rate is 5.82 MHz and the measured pulse width is 87 ps. The spectral central wavelength is 1549.3 nm, the 3 dB spectral width is 0.06 nm and the signal-to-noise ratio is 66 dB.