Impulse grounding impedance is a significant factor which affects the level of lightning protection and lightning trip-out rate of transmission lines.At present

the simulation method or reduced-scale experiment is often used to study impulse grounding impedance characteristics

however it could not obtain the real situations.It is important to use full-scale experiment to get impulse grounding impedance characteristics of the grounding electrode.Various forms of grounding electrode were chosen as research object in this paper

discussing the effect on the impulse characteristics of grounding electrode

such as impulse current amplitude and size of grounding electrode.EMTP simulation model of impulse grounding impedance of grounding electrode was established.When the amplitude of impulse current increases

the length of grounding electrode increases or the cross-section diameter increases

the impulse grounding impedance will decrease

and the influence of the length of grounding electrode and the amplitude of impulse current will be lead to saturated.The simulation results show that the simulation model of impulse grounding impedance of grounding electrode based on the model of piecewise π equivalent circuit can effectively calculate the impulse grounding impedance of grounding electrode.