Abstract: Lightning striking has become the primary factor that threatens the safe and reliable operation of the power system, and the transmission lines with voltage levels of 500 kV and above are mainly affected by lightning shielding failure. On the basis of summarizing the development of electro-geometric model and to overcome the problem that electro-geometric models ignore most of the physical processes of lightning strikes, this paper provides a detailed analysis of the leader propagation model (LPM), including the physical process of lightning strikes on transmission lines, parameter selection of the model, numerical implementation, and model validation. The factors affecting the shielding failure of transmission lines are analyzed, and the applicability of different shielding failure analysis methods is discussed. For transmission lines with voltage levels of 500 kV and above, as well as multi circuit transmission lines on the same tower, the leader propagation model should be used to analyze the lightning shielding failure rate. This paper provides important technical support for lightning protection design and operation accident analysis of transmission lines.