X-ray flat panel detector, well accepted as image receptor of digital X-ray image system in Medical, Non-destructive Testing and Security applications, has been improved significantly in the past 20 years. From indirect conversion to direct conversion in technology, from a-Se to a-Si, IGZO and flexible in material, from GOS to CsI in scintillator, from tethered static to wireless and high speed in data transmission, X-ray flat panel detector has been improved in many technology. Meanwhile, with the maturity of the supply chain in China, the localization rate of X-ray flat panel detector increases every year, and the trend of industrial chain transfer appears.