The spectacular progress made during the last few years in rod-pinch diode(RPD) research opens new perspectives of flash X-ray radiography, especially in the small-scale hydrodynamic experiments. This survey covers essentially all aspects of RPD with various configurations (i.e. vacuum RPD and plasma-filled RPD): basic principle, scaling laws, significance and applications. The parameters and experimental results of the Cygnus underground facility are introduced. The development of RPD in the near future is also stated and discussed.