In order to realize a tunable dual-wavelength laser output,an Er³⁺- doped fiber laser based on self-feedback light injection is proposed,and the theoretical analysis and experimental verification are pres ented in detail.In the designed configuration,one 976nm laser diode (LD) is used for pumping,Er³⁺-doped fiber (EDF) is adopted as the gain medium,the laser cavity is composed of a fiber loop mirror (FLM) and two FBGs,and a saturable absorber (SA) is used to improve the output laser stability.In order to improve the laser stability and restrain the mode hopping,the output laser f rom FLM is used as self-feedback light which is coupled into the cavity by a 90∶10coupler.The interference is shown whe n injection light and oscillating light transmit in the cavity,a weak Bragg grating is generated and some certain waves can be restrain ed,so that a fiber laser with stable output is achieved. A switchable single-wavelength and dual-wavelength laser is achieved by adjust ing the variable attenuator between two FBGs.In the experiment,an EDF of 4m length is selected as the SA,and an EDF of 6m length i s adopted as the gain medium.In the end,the threshold is reduced from 28mW to 25mW after self-feedback light is injected into the cavi ty.When pump power is 80mW,a stable tunable dual- wavelength output is realized by adjusting the variable attenuator (VA).When the pump power is improved,the single wavelength laser at 1540nm and 1545nm is measured and the po wer is 1.16mW and 1.89mW,respectively,and the SNR is greater than 50dB.A stable and tunable dual-wavelength Er³⁺-doped fiber laser is achieved by self-feed back light injection structure and SA,which can optimize the system and improve the working efficiency.