the characteristics of lighting stroke fault of ±500 kV Jiangcheng transmission line is analyzed in this paper.The results show that the oversize design span and shielding angle and side slope effect are the primary cause of lightning trip-out for ±500 kV Jiangcheng line.The lighting protection countermeasures of reducing shielding angle and installing lighting arrester are put forward according to design and reform of lighting protection for DC transmission lines.