Abstract: This paper summarized the geometry and principle of the rod-pinch diode. Using Laminar model and considering the effect of background ion space charge on the one dimensional, Laminar equilibria of relativistic, magnetically self-insulated, electron flow is presented. Both positive and negative polarity diodes are simulated using MAGIC program, the current and voltage have also been solved through numerical simulation method. Results from numerical simulation are consistent with the calculations. In particular, it is shown that, as the voltage is the same, the self-pinch of negative rod-pinch diode is more difficult than that of the positive rod-pinch diode. Finally the characteristic impedance is detruded, the feasibility of laminar model has been validated.