Electromagnetic time reversal (EMTR) is mostly applied to single line fault localization, and the existing criterion is not satisfactory in the case of high impedance grounding. To address the above problem, this paper derives the transfer function of the line fault and measurement signals in the propagation process based on the EMTR fault localization principle and uniform transmission line theory. It proposes a P-parametric criterion based on the correlation of the transfer function. The ATP-EMTP is used to build 10 kV distribution lines to compare the localization performance of the 2-parametric and P-parametric criterion in complex distribution networks, and to verify the applicability of the proposed criterion in hybrid distribution lines. Finally, the robustness of the P-parametric criterion is analyzed in the cases of occurrence of low and high impedance ground faults in distribution networks. Simulation results show that the method can locate accurately with transition resistances as high as 3 k with high accuracy, and is less affected by noise, fault type and sampling frequency.