Abstract: The present paper focuses on a 220 kV line tripping issue. A detailed investigation into the operational data and fault characteristics of the line has been undertaken, with the aim of explaining the causes of the line tripping. The investigation has revealed that the causes include equipment ageing, adverse weather conditions, and external short-circuit fault impacts. In response to these issues, a series of practical and feasible countermeasures are proposed, such as optimizing the configuration of protective devices, strengthening line inspection and maintenance, and enhancing fault rapid localization and isolation technologies. The objective of these measures is twofold: Firstly, to enhance the reliability and stability of the 220 kV line's power supply, and secondly, to ensure the safe and stable operation of the power system.