Yb-doped silica glass preforms are fabricated by modified chemical vapor deposition process combined with the solution doping technique. Preform core diameter fluctuation is less than 5% and index difference fluctuation is less than 8% along axial direction. 20/400 double-clad Yb-doped optical fibers are drawn after grinding with core non-circularity of 2% and core/clad offset of 0.87 μm. The cladding attenuation of Yb-doped optical fibers at 1095 nm is 2.1 dB/km. The cladding pumped all-fiber laser oscillator is demonstrated using Yb-doped double-clad fibers. Fiber lasers with output power of 1195 W and slope efficiency of 82% are obtained.