Abstract: In order to explore the feasibility of low density imaging of rod pinch diode (RPD) under impact loading, a simulation study on physical properties of RPD under low voltage operation (≤500 kV) is carried out. Based on particle-in-cell (PIC) simulation method, a simulation is carried out on amplitude of loading voltage of diode, thickness of cathode plate, aperture ratio of cathode and anode, etc. The physical process of pinch is analyzed according to the angle of electron pinch efficiency, proton flow, electron utilization, electric field and magnetic field distribution. The simulation results show that the current of RPD is low under low voltage operation, and can't provide enough magnetic force for the electron, resulting in low electron pinch efficiency. It is a technical approach to realize high dose and small focal spot light source under low voltage condition by using composite rod-pinch diode and optimizing design of the transition region of anode rod to bremsstrahlung target region.