Large area well-aligned ZnO nanorod arrays on different substrates were synthesized by hydrothermal methods. The electron emission properties of the ZnO nanorod arrays on different substrates were investigated under both direct current (DC) and pulse electric fields. Owing to the excellent conductivity of substrates, the array on stainless steel substrate had better electron emission properties than that on silicon substrate. Under the DC and pulse electric fields, the electron emission of arrays had different production mechanisms which were pure field emission and plasma-induced emission respectively. During the plasma-induced emission, the plasma formed on the array surface, and the maximum emission current density of arrays on stainless steel was 118.87 A/cm2. The plasma-induced emission of ZnO nanorod arrays were always distributed uniformly. In this work, the results show that the ZnO nanorod arrays are expected to be applied to different electronic devices as electron beam sources under different electric fields.