Based on the vertical electric dipolar emitter source model, the far-field characteristics of seismic electromagnetic radiation are studied first, and then the relationship between the radiation intensity of far-field seismic electromagnetic and pregnant earthquake magnitude is analyzed. The results show that the vertical electric dipolar emitter source model can be used to interpret the phenomenon of electromagnetic radiation emitting in seismogcnie zone, and is one of the most possible source mechanisms for emitting the seismic electromagnetic radiation field. The logarithm of radiation intensity of far-field seismic electromagnetic has linear relation to earthquake magnitude, and the lineg slop has relation with the fracture distribution and fracture electromagnetic characters in seismogenie zone. The results of this paper are significant for knowing the phenomenon of seismic electromagnetic radiation and useful for earthquake prediction.