A fault nature identification method for single-phase adaptive reclosure on UHAVC transmission lines with shunt reactors is proposed by considering bandpass characteristics of the voltage transformer and power frequency component in the power system. By using the ATP-EMTP software the arc model is built. Then, the attenuation factor is extracted by Prony algorithmand the attenuation factor ratio in fixed time window is calculated with Prony algorithm. Finally, the identification strategy which can distinguish the permanent fault and intermittent fault is put forward by comparing the difference of attenuation ratio factor. A lot of calculation results and simulation results show that wherever the fault location is, the transient fault and permanent fault can be correctly and effectively identified.