Flash X-ray radiography is often used to photograph the internal structure and hydrodynamic behavior of high-speed moving objects, and has gradually expanded to the fields of industrial flaw detection, precision system state detection and so on. This paper summarizes the research process and progress of small flash X-ray machine (SFXM), relating to four main technical routes of Marx generator, pulse forming line, fast pulse linear transformer, high-voltage transformer, and two key components of X-ray diode and switches. The research status of small flash X-ray radiography system is discussed, and the shortcomings of mature commercial small X-ray machines abroad and domestic commercial products are explored, The development trend of SFXM in the future is analyzed, which provides reference and basis for the research and development of SFXM and the exploration of commercial popularization.