The all-fiber passively mode-locked erbium-doped femtosecond fiber lasers based on semiconductor saturable absorber mirror (SESAM) and graphene oxide saturable absorber mirror (GOSAM) in the same cavity are demonstrated. The fiber ring laser is constituted with 1.4 m Er3+-doped fiber as gain medium, which is pumped by 974 nm diode laser, and with the total cavity length of 12 m. Stable mode-locked laser pulse train occurrs at 29 mW incident pump power by employing GOSAM as the saturable absorber. The pulse width is measured to be 703 fs, and the center wavelength is 1557.67 nm, and 3 dB spectral bandwidth is corresponding to 3.91 nm. However, inserting SESAM with a modulation depth of 18% in the configuration mentioned above, we can obtain ultrashort pulse at 32 mW pump power, and the pulse width decreases to 542 fs. The laser center wavelength and the 3 dB spectral bandwidth are 1561.5 nm and 5.41 nm, respectively. Experimental results show that the novel mode-locking device—graphene oxide has the similiar distinguished saturable absorber ability. With its advantages of low price, simple preparation, it seems to be a good candidate for saturable absorbers in achieving ultrashort pulse operation.