UHV transmission line is long, so the secondary arc is hard to quench. If single-phase automatic reclosing fails, system security and stability will be impacted. Therefore, it is necessary to study the secondary arc current for UHV transmission lines. Taking 1 000 kV transmission lines from Nanyang to Jingmen as the research object, the simulation model is established in this paper to calculate the length of transmission lines, the fault location and the influence of arc resistance on secondary arc current, by applying ATP-EMTP. Finally, the application effect of two methods of extinguishing secondary arc current, high speed grounding switch and shunt reactors with neutral reactor, are compared for the EHV and UHV transmission lines with shunt reactor.