Abstract: The distribution of power frequency electric field in the substation under the influence of the earth electrode is studied in this paper. Firstly, the charge simulation method for the calculation of power frequency electric field in switch yard is derived in this paper, and the electric field of 500kV switch yard is analyzed in a 500kV substation with the earth electrode. Secondly, the modeling of the substation is established. Finally, numerical results are compared to that of measurement for verifying the correctness of the model; then the power frequency electric field distribution in switch yard is analyzed whether the earth electrode of electrical equipment. This work provides an effective, efficient way for the calculation and analysis of the power frequency electric field in the substation with the existence of earth electrode.