In order to investigate the electric field distribution problems under 500kV EHV transmission lines and establish the same tower double circuit transmission line model after verifying the effectiveness of the finite element electromagnetic field analysis software Ansoft maxwell . The paper mainly analyze the influence of the phase conductors to ground height , split wire structure size and other factors on the characteristics of the electric field , and the variation of the line electric field distribution when a fault occurs or outage maintenance, which is to provide a theoretical basis and methods for reducing the transmission lines around the farm and the optimization of the electromagnetic environment, At the same time ,it provides a reference for power line maintenance considerations.