In this paper, the electromagnetic environment for the surrounding of the double-circuit line of a 750 kV substation is studied. Based on the double-circuit overhead transmission line model, the influences of the distance of phase conductors, numbers and spacing of the split conductors, the diameter of the sub-conductor, and the conductor to ground height, on the electric intensity of conductor surface, the radio interference(RI), and the audible noise(AN)are analyzed. Measures to improve the electromagnetic environment are proposed as well.