In order to ship model the Shaft-ELFE in shallow sea, the basic simulation unit-time-harmonic horizontal electric dipole was taken for example, the Hertz vector potential was solved based on the uniqueness principle combined with boundary conditions. The electromagnetic field in shallow seawater was derived from the relational expression between Hertz vector potential and electromagnetic field. The electromagnetic field distribution of DC dipole in three media was solved. The simulated results show that the horizontal electric cell can be used to compute the harmonic cell at sufficiently low frequencies between 1Hz and 7Hz. The conclusion was further confirmed in laboratory, utilizing the horizontal electric cell and the horizontal harmonic electric cell source in man made seawater. Finally, the shallow marine environment and horizontal time-harmonic electric dipole were simulated in the laboratory, the electric field distributions of time-harmonic electric dipole and DC dipole were compared. The results show that the time-harmonic electric dipole electric field distribution was consistent with the theoretical calculation, which proved that the derivation and analytical expression are correct; the horizontal time-harmonic current model can be replaced by horizontal DC dipole when the envelop of shaft-ELFE is simulated, and has a higher accuracy and practicability.