The transmission spectrum of Sagnac comb-like filter based on high-birefringence polarization maintaining fiber (PMF) and Sagnac fiber loop mirror can be tuned easily. A novel switchable wavelength erbium-doped fiber ring laser by using this filter is proposed. By adjusting two polarization controllers (PCs) within filter properly, a single-, dual-, triple-, quadruple-wavelength laser beam can be obtained at room temperature in experiment. The principle of stable operation at room temperature is based on inhomogeneous broadening effect induced by a deeply saturated effect in the erbium-doped fiber. The wavelength interval is 1 nm, which can be optimized by using proper PMF length.