Abstract: To study the generation of ultrashort pulse in Er3+-doped fiber laser,the fiber laser was composed of a gain-flattened erbium doped fiber amplifier(EDFA),two polarization controllers(PCs) and three couplers.A nonlinear optical loop mirror was used for mode-locking.By adjusting the position of PCs,the pulse at 1561nm at a repetition rate 1.1MHz was obtained.The maximum output power of the pulse was 0.6mW with 434ps pulse width and 9nm spectrum width.After amplified by EDFA,the maximum power of the output pulse is 10.8mW and the center wavelength did not change,the spectrum width became slightly narrow,the output power increases greatly and the pulse width of the amplified pulse was 495ps.The experimental results show that:the ultrashort pulse could be generated by the Er3+-doped fiber laser using a commercial EDFA.The self-starting of the mode-locked fiber laser can be achieved easily and the mode-locked operation can be hardly influenced by the experimental environment.