A few-mode ring fiber laser based on an all-fiber mode multiplexer/demultiplexer (MUX/DEMUX) was designed, which achieved switchable lasing output in LP₀₁, L P11, LP₂₁, and hybrid modes. Experimental results show that the output lasing mode of the ring fiber laser can be switched between the three lowest-order linearly polarized (LP) modes and hybrid modes by employing a low mode-crosstalk all-fiber mode MUX/DEMUX and a simple 4 × 1 optical switch. Thresholds of 40, 60, and 80 mW and slope efficiencies of 1.2%, 0.82%, and 0.56% were obtained for the LP₀₁, LP₁₁, and LP₂₁ mode operations, respectively. Numerical simulation and parameter optimization of the designed few-mode ring fiber laser structure adequately resolved the wavelength shift problem, with a line width of 3 dB less than 0.032 nm being realized.