In order to avoid the damage caused by the blind recloser of the automatic reclosing in the permanent fault after the phase-to-phase fault trip of the distribution line, this paper proposes a method for identifying permanent faults between phases in distribution networks based on parameter identification. This method is used after the three-phase tripping of the power distribution line, the low-frequency voltage disturbance signal is actively applied to the three phase-to-phase loops of the power failure line in turn, the current and voltage information of the excitation side are used to establish the parameter equation of the interphase loop, and the parameter identification idea is used to screen the state of the interphase loop. The fault-free phase-to-phase loop is used as the calculation model. The nature of the fault is judged according to the deviation between the identification value of the resistance and inductance parameters and the true value in the actual loop. When the recognition value deviates greatly from the true value, the actual phase-to-phase loop model is in line with the calculation model, and it is judged as a permanent fault. The simulation calculation results based on PSCAD show that the permanent fault identification method studied in this paper can effectively identify the nature of the fault, and is basically not affected by factors, such as transition resistances and fault locations which is helpful to realize the three-phase adaptive reclosing of the distribution network.