An all-fiber high-power fiber laser with home-made 20/400 double cladding Yb-doped fiber(DCF) was reported.The laser output uses resonant cavity mode,and its central wavelength is 1080 nm,the maximum output power is 758 W,the output spot diameter is 6~8 mm,the β factor is 1.3;the electro-optical conversion efficiency is 36.7%,and optical-to-optical efficiency is 71%.After 32 hours of laser output,the fluctuation range of average output power is less than 2%.