Rare earth-doped fiber lasers are interesting in the field of optical fiber lasing and sensing. One of the interesting topics is the tunable/switched multi-wavelength lasers. However, due to the homogeneous broadening gain, it is difficult to generate multiple wavelengths in the fiber lasers based on erbium-doped fibers. Here, we propose a tunable multiwavelength erbium-doped fiber ring laser based on an optical fiber tip Fabry-Perot (FP) interferometer, which acts a wavelength filter and a reflector of the fiber ring laser. With the purpose to propose a method for switch multiwavelength spectra, the strain and thermal variations around the modal interferometers are investigated. The spectra are symmetric with a maximal power difference about 25 dB between the lasing modes and the average of the side mode suppression ratio, which is tuned into the C-band with a resolution of 0.02 nm. This laser offers low wavelength drift, good signal to noise ratio and high-power stability, and can therefore be used for sensing applications.