Large to observe the boundless expanse of universe with astronomical optical telescopes, small to detect the infinitesimal nanoworld with optical microscopes, optical imaging technology plays a very important role for human beings in the exploration and discovery of the mysteries of the unknown world. To see farther, to see more details and to see more clearly are people′s constantly pursuing goal. The traditional optics theory has proved that all classical optical systems are diffractionlimited, i.e., the physical limit of the spatial resolution of optical systems is determined by the light wavelength and the relative aperture (or numerical aperture) of the system. Can this diffractionlimited barrier be broken through? Is it possible to continue to improve the imaging resolution of optical systems? Around this issue, this paper reviews the recent progress of a variety of highresolution and superresolution optical imaging techniques, and their developments in the fields of space exploration and biological applications.