The ytterbium-doped silica fiber is one of the important basic element of fiber laser and amplifier system. The key to promote the further increase of fiber system power is the performance improvement of ytterbium-doped fibers. In this paper, the power increase and main challenge to power scaling of high power ytterbium-doped fiber laser system are reviewed, and the improvement scheme for the bottleneck problems of laser power climbing is briefly described. The research progresses in improving power restriction based on fiber fabrication technology, optical fiber material and fiber structural design are described in detail. Furthermore, the future research and development tendency of ytterbium-doped silica fiber are prospected.