Abstract: The wideband wide-angle scanning theory and technique of planar phased array is the core topic and key technique in the field of antenna and radio wave propagation, and plays an important supporting role in high-performance radar, communication, navigation and other information systems. It is shown that the bottlenecks that restricts the wide-angle scanning of planar phased arrays are mainly the element beam shape, array arrangement, and coupling relationships in scanning arrays. In this paper, from the above three aspects, we review the development history of the wide-angle scanning theory and technique of planar phased array, and makes a prospect of its research and development.