The existing charge distribution models of the lightning channel are as follows: 1) Dipole model; 2) Charged disk model; 3) Exponential distribution model; 4) Linear distribution model. The dipole model and the charged disk model are derived from the ground electric field detector, and the exponential distribution model and the linear distribution model are deduced from the macroscopic phenomena of lightning development. The development of lightning channel is a streamer breakdown process with stepped charge-discharge, so the current charge distribution models of the lightning channel cannot accurately describe the development process of lightning channel. In the previous model, the drawbacks of several models are also verified, and the development shape of lightning in the model is significantly different from the actual situation. With resistance, capacitance, and inductance of the distributed-circuit model has been widely applied to simulate the lightning return stroke process, this model is now applied to simulate the development process of the lightning channel, and the lightning channel is regarded as multi-stage plasma developing step by step. Each section of plasma is charged - discharged - charged in turn, then determine the resistance, capacitance, and inductance values to build a discharge circuit. This paper presents a new model of charge distribution in the lightning channel – stepping distribution model, in which capacitance is calculated using average potential method and impedance is calculated by Neumann formula, they are functions of frequency, time, and coordinate. The circuit model was built by using EMTP software, and the dipole model and the linear distribution model of charge are brought in to invert the values of resistance, capacitance, and inductance. Then the current waveform is observed, and it is found that the waveform obtained under these two models could not accurately reflect the lightning shock wave. The stepping distribution model proposed in this paper can more accurately restore the lightning current impact waveform. In previous studies, it is found that charge distribution models of the lightning channel proposed earlier cannot accurately describe the discharge process of the streamer inside the lightning channel. The stepped distribution model proposed in this paper reflects the collision process of various particles when lightning occurs in the parameters of the element. The lightning impulse waveform observed from the model is more restored to the image recorded by the original data, but the lightning current in the latter part of the waveform is still at a relatively high value, which may be caused by the incomplete discharge of the initially set capacitor.

lightning channel; charge distribution of the lightning channel; distributed-circuit model; stepping charge distribution model; lightning shock wave