Hartmann-Shack wavefront sensors are widely used in adaptive optical systems. It can measure the spatial-temporal errors of dynamic wavefront. Not only the phase but also the amplitude of a wavefront can be measured. Unlike an interferometer, it is not necessary to have a real-time reference beam, so it can work in a disturbing environment. Besides used in adaptive optics systems, Hartmann-Shack wavefront sensors also become a powerful tool in two fields: light beam diagnosis and optical testing of optical components and systems. We have developed a serial of Hartmann-Shack wavefront sensors used in these two fields. In this presentation, various applications of Hartmann-Shack wavefront sensors in these fields will be reported.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.