ZnO nanorod arrays were grown on Si substrate by a simple two-step process with sol-gel and hydrothermal methods. To investigate the effect of seed layers on the growth of ZnO nanorods, different numbers of the seed layers have been spin-coated on the substrates. The morphologies of ZnO nanorods including diameter, density, length, and orientation have been studied. The crystallization and band structure have also been discussed. The correlation between the nanorod arrays grown on different seed layers and field emission (FE) properties has also been analyzed. The ZnO nanorod array grown on 4 seed layers possesses the best field emission properties, including a lowest turn-on electric field of 13.3 V/mu m and largest field emission current. It can be attributed to the higher field enhancement factor, the vertical orientation, larger density, and better conductivity of the nanorod arrays. (C) 2015 Elsevier B.V. All rights reserved.