Abstract: Under the irradiation of the 5G base station antenna, the densely distributed electrical equipment in the substation will produce strong secondary scattering phenomenon due to the coupling effect, which inevitably affects the solution of the electromagnetic scattering field in the substation. Therefore, on the basis of solving the electromagnetic scattering field of a single target, and considering the electromagnetic coupling effect between multiple scatterers, a spatial scattering field solving algorithm for any point in the background of a large number of metal equipment arrays in substations is proposed. First, the electrical equipment of the substation is partitioned, taking into account the mutual coupling between devices within a range of 10 times of the electromagnetic waves length in each area, in order to identify the device clusters that need to be considered for coupling. Then in the divided equipment cluster, the electric field equation of the secondary scattering field between two adjacent sets of equipment is derived according to the field and source reciprocity relationship of the scattering electric field. By superimposing the primary scattering field generated by the 5G base station antenna and the secondary scattering field generated by coupling effect, the spatial scattering field of the electrical equipment cluster coupling in the substation is finally obtained. Taking the 500 kV Guandu substation as an example, the average error between the calculated and measured electromagnetic scattering field values after considering the mutual coupling of electrical equipment in the substation is 6.39%, while the average error value without considering the equipment coupling algorithm is 43.64%. This algorithm achieves accurate solution of electromagnetic scattering field in substations under the radiation of 5G base station antenna.