Abstract: To solve the problems of the lowest cut-off operating frequency being higher, low gain and poor directivity of the traditional antipodal Vivaldi antennas (AVA), an ultra-wideband multi-octave exponentially tapered AVA is proposed in this paper. Through the fusion of a series of electromagnetic control measures, such as notching rectangular slots on the radiating plate and loading absorption resistance and parasitic rectangular patches, the low frequency impedance matching has improved significantly. In addition, parasitic ellipse element is integrated into the center of exponential taper slot without sacrificing size. A substantial increase in directivity and gain of the entire frequency band is achieved. Three design steps of the proposed AVA are employed, and the working principle from the perspective of electric field and surface current distribution is analyzed. The simulated and measured results are in good agreement, which show the bandwidth ranges from 0. 85 to 16 GHz (nearly 20 octave) and the relative bandwidth is about 180%. The realized gain is more than 10 dBi in the operation bandwidth of > 3 GHz. The proposed AVA has the advantages of simple design, easy fabrication and excellent performance, which provides practical significance for the research of ultra-wideband end-fire antenna with low cut-off frequency and high directivity. The design can be widely used in the ultra-wideband wireless communication, radar detection, electronic counter measures and remote sensing applications.