A saturable dual-wavelength laser based on a saturable absorption ring filter is designed. An unpumped erbium-doped fiber is inserted into a 3 dB ring mirror to form a saturable absorption ring mirror filter, which is inserted into a ring laser to achieve a stable dual-wavelength output by adjusting the polarization controller. After calculation,6.4 m erbium-doped fiber is selected as the gain medium, and a section of 2 m unpumped EDF is used to form a saturable absorption loop mirror filter in combination with a 2×2 3 dB coupler to suppress the supermode. In order to suppress the mode competition caused by the uniform widening of erbium-doped fiber at room temperature,1554 nm fiber Bragg grating (FBG) and 1562 nm FBG are selected for dual-wavelength lasing. Simulation is conducted on the Optisystem platform and experiments are set up to test the output laser power, signal-to-noise ratio, stability, etc. The output signal is observed and analyzed with a Optical Spectrum Analyzer. In the experiment, the stable output of dual-wavelength laser at room temperature is obtained, and the signal-to-noise ratio of the two wavelengths is 54.70 dB and 57.50 dB respectively. The 3 dB bandwidth is about 0.13 nm.