This book comprehensively and systematically introduces lightning protection technology for transmission lines, focusing on clarifying the discharge characteristics and electromagnetic transient propagation mechanism of the entire physical process when a lightning strike occurs on a transmission line, from the lightning downward leader striking the line, the lightning current flowing through the line and the pole tower, and then entering the ground through the grounding device. It introduces the electromagnetic transient analysis models of insulators, lines, pole towers, and grounding devices, as well as the calculation methods for the entire physical process of lightning strikes on transmission lines. It also covers protective technologies such as grounding devices, parallel protective gaps for insulators, line arresters, and unbalanced insulation for multi-circuit lines on the same tower. Finally, it introduces the latest research trends in monitoring and identification of lightning faults on transmission lines. The book is divided into 11 chapters, systematically reflecting the relevant scientific research results of the author’s research team over the past three decades, and also covering the research work and latest research trends of scholars both domestically and internationally in the field of lightning protection for transmission lines.