We demonstrate an all polarization-maintaining (all-PM) mode-locked ytterbium-doped fiber laser (YDFL) based on a semiconductor saturable absorber mirror and nonlinear polarization evolution. The laser can produce tunable dual-wavelength from 1019.75 nm to 1038.68 nm, and triple-wavelength from 1021.28 nm to 1038.35 nm. To our knowledge, this is the first report of tunable dual- and triple-wavelength mode-locked operation in all-PM mode-locked YDFL. Furthermore, numerical simulations have demonstrated the multi-wavelength genesis and dynamic evolution. Our research proposes an innovative approach to achieving tunable multi-wavelength in all-PM fiber laser and lays the groundwork for a new type of all-PM tunable stabilized laser source.