In order to meet the demand of THz vacuum devices for miniature electron beam with high current density, a kind of miniature cathode has been prepared by depositing Ta/Zr coating on impregnated scandate cathode surface via dual Ion-Beam-Assisted Deposition (Dual IBAD) and etching an emission zone with a diameter of 100 m via Focus Ion Beam(FIB). Based on the previous study, this paper focuses on the characteristics of anti-emission coating. It is shown in the experimental results that Ta/Zr coating prepared by dual Ion Beam Assisted Deposition(Dual IBAD) can suppress electron emission more effectively and has a longer life time than that prepared by magnetron sputtering. The reasons for the sound anti-emission performance are that composition with high work function is formed in the process of Barium diffusion into the Ta/Zr coating, and that Barium diffusion is effectively suppressed by the high dense Ta/Zr coating.