[en] The impedance and X-ray radiography states are the main references of rod-pinch diode. In order to study the physical performances of rod-pinch diode, a PIC and photoelectron transport simulation based on Monte Carlo is used to simulate the physics of the 1.2 MV X-ray generator Scorpio rod pinch diode at Institute of Fluid Physics, CAEP. The influence of structure parameters, including anode-cathode radius rate and anode rod stretching out length, on the diode impedance and radiography is given. The simulation results show good uniformity with theory and experiment. A model is proposed to increase the radiation dose rate, which might be applied in the future design of rod-pinch diode. (authors)