The invention provides a method and a system for predicting electromagnetic coupling degree among antennas on a dielectric-coated target. The method includes: S1, decomposing total field of the antennas with a uniform geometrical method of diffraction of electromagnetic waves to acquire diffraction field and surface wave field generated by dielectric, and acquiring electromagnetic wave reflection properties of the dielectric; S2, utilizing an antenna port network model to acquire electromagnetic wave scattering coefficients between two ports on the basis of the diffraction field, the surface wave field and the electromagnetic wave reflection properties of the dielectric, so as to predict electromagnetic coupling degree among the antennas on the dielectric-coated target. By analysis on electromagnetic coupling paths of the antennas on the dielectric-coated target, the total field of the antennas are decomposed rationally, and qualitative analysis and quantitative denotation are performed on electromagnetic coupling degree under the diffraction field and the surface wave field with the antenna port network model so as to predict the electromagnetic coupling degree among the antennas on the dielectric-coated target.