We　demonstrated　an　all-fiber-integrated　linearly-polarized　picosecond　ytterbium-doped　master-oscillator　power-amplifier　system,　which　yielded　225-W　of　average　output　power　and　the　corresponding　slope　efficiency　is　70.5%.　The　seed　source　was　a　compact　passively　mode-locked　polarization-maintaining　ytterbium-doped　all-fiber　oscillator　with　a　pulse　duration　of　80-ps　at　58.2-MHz　repetition　rate.　In　combination　with　two　pre-amplifiers　and　a　large-mode-area　polarization-maintaining　ytterbium-doped　all-fiber　master　amplifier,　output　pulse　energy　up　to　3.8-mu　J　with　48.3-kW　pulse　peak　power　was　obtained　without　the　need　of　complex　free-space　coupling　and　output　setups.　The　polarization　extinction　ratio　were　measured　to　be　14.5　dB　and　the　beam　quality　M-2　factors　was　less　than　1.49　in　the　both　orthogonal　directions　at　maximum　output　power.