The model of the charge pile based on the three phase diode bridge rectifier and the DC/DC high-frequency isolated converter is built and simulated in PSCAD, then the load characteristic of the charge pile is analyzed. Based on the analysis of the way how users use their electric vehicles, the Monte Carlo method is applied to find out the daily load curve of 1 500 electric vehicles' charging power. Considering the charging load's characteristic and its influence on the current protection of the power distribution line, the over current protection based on the reactive power fault component is proposed. The detailed setting method and the operation characteristics of the protection are given. The protection scheme is simulated using PSCAD, and the simulation result verifies the effectiveness of the proposed line protection scheme of the distribution network including large-scale electric vehicles.