Abstract: Dipole antenna is one kind of common shortwave antenna. Its response characteristics exposed to high-altitude nuclear electromagn etic pulse (HEMP) is simulated using CST in this paper. The response characteristics of a dipole antenna's port when it is open and terminated 50 Ωload are calculated in free space and over a conductor plane. Induced voltage in the time domain and frequency domain signals and deposited energy obtained in both cases are made out. And its variation with angle of incidence of electromagnetic pulse θ, conductor plate radius R and antenna height H are explored. The simulation results have important guiding significance for the experimental program and protection of the antenna system.