We　demonstrated　a　linearly-polarized　picosecond　thulium-doped　all-fiber-integrated　master-oscillator　power-amplifier　system,　which　yielded　240　W　of　average　output　power　at　127　MHz　repetition　rate.　The　seed　source　is　a　passively　mode-locked　polarization-maintaining　thulium-doped　all-fiber　oscillator　with　a　nearly　transform-limited　pulse　duration　of　10　ps.　In　combination　with　a　pre-chirp　fiber　having　a　positive　group　velocity　dispersion　and　a　three　stage　polarization-maintaining　thulium-doped　all-fiber　amplifier,　output　pulse　energies　up　to　1.89　mu　J　with　42　kW　pulse　peak　power　are　obtained　without　the　need　of　complex　free-space　stretcher　or　compressor　setups.　To　the　best　of　our　knowledge,　this　is　the　highest　average　output　power　ever　reported　for　a　picosecond　all-fiber-integrated　laser　at　2　mu　m　wavelength　region.　(C)　2016　Optical　Society　of　America