Abstract: In this paper, a new method is proposed to establish the equivalent source model of the radiation emission of the electronic device under test by using near-field scanning technology. The model is based on a set of magnetic dipoles that can replace the device under test and radiate approximately the same magnetic field distribution. In order to determine the model parameters, the differential evolution algorithm is used to determine the position of the magnetic dipole and the magnitude of the magnetic dipole moment through the magnetic field intensity amplitude measured in the near field. In order to further improve the efficiency of model building, an optimization method is proposed to limit the location search range of magnetic dipoles according to the hot spot range of the total magnetic field intensity of the device under test. This method improves the efficiency of model building without significantly reducing the accuracy of the model. The proposed method is used to establish the equivalent source models of the circular patch antenna and the microcontrol unit respectively, and the effectiveness of the proposed method is verified. The results show that the equivalent source model can be established quickly and accurately describe the radiation characteristics of the device under test.