Abstract: For their high emission current density and relaxed operation environment, the ferroelectric cathode materials were made a point of studying as the novel functional materials by the scientists. In order to obtain the data of the current densities, the ferroelectric cathode vacuum diode was designed and developed. The lead zirconate titanate （PZT） ferroelectric material was packaged into the vacuum diode. The study of the electron emission was carried out. The results show that the vacuum degree is up to the scratch and the disturbing signal of earth current is screened. Therefore, the vacuum diode is passed the requirements of the electron emission current density measurement.