We　investigate　the　stimulated　Brillouin　scattering　(SBS)　effect　in　high-power　thulium-doped　fiber　amplifier　seeded　with　a　narrow-linewidth　fiber　superfluorescent　source　or　a　conventional　narrow-linewidth　fiber　laser.　No　random　backward　SBS　pulses　are　observed　when　using　a　narrow-linewidth　fiber　superfluorescent　source　as　the　seed.　The　corresponding　average　power　and　peak　power　reach　153　W　and　3.4　kW,　respectively,　only　limited　by　the　available　pump　power.　This　gives　the　average　power　and　peak　power　extraction　from　the　thulium-doped　fiber　amplifier　with　17　fold　enhancement,　in　comparison　with　the　situation　using　the　conventional　narrow-linewidth　fiber　laser　with　similar　central　wavelength　and　spectral　linewidth　as　the　seed.　This　work　indicates　that　using　low　coherent　fiber　superfluorescent　sources　is　a　good　solution　for　power　scaling　in　narrow-linewidth　fiber　amplifier　system　in　order　to　overcome　the　limitation　of　SBS　effect.　(C)　2017　Optical　Society　of　America