This paper describes a broadband dipole antenna based on the single negative(SNG) transmission line.By loading SNG transmission line structures on both arms of the dipole antenna,the current distribution on the surface of the antenna has changed.And the zeroth-order and firstorder resonance was tuned close enough to make the “dual resonance” phenomenon by choosing appropriate capacitance and inductance,thus resulting in the bandwith enhancement of the traditional dipole antenna.The HFSS simulation result shows that the -10 dB bandwidth of the antenna reaches 1.7 GHz(2.3~4.0 GHz) and the relative bandwidth is up to 54%，which is a magnificent progress of the bandwidth enhancement for the dipole antenna.The radiation patterns within the impedance bandwidth shows good consistence, and the gain reaches as high as 2~3 dBic.