In order to solve the problem of the permanent failure of the automatic coincidence gate in the EHV transmission line with shunt reactor,the frequency of the frequency of the voltage in the recovery voltage is found to exist in the frequency of 30-45Hz.According to the characteristic of the frequency,the characteristics of the fault characteristics of the EHV single phase adaptive based on the PRONY algorithm are proposed.Using the PRONY algorithm to calculate the frequency of the recovery voltage signal,so as to quickly and accurately identify the transient faults and permanent faults.Simulation and experimental results verify the validity and accuracy of the criteria.