Highly ordered ZnO nanorod arrays were successfully synthesized on glass substrates coated by the ZnO seeding via a chemical method, and the effect of the polyethylenei mine(PEI) on the structural properties and morphology of ZnO nanorod arrays was investigated. The XRD and FESEM results showed that the ZnO nonorods were wurtzite structure, which was hexagonal in shape. And the nanorods grew densely and vertically on the substrate. With the PEI amount increasing, the average diameter of the nanorods decreased, and the growth rate was slower. The Raman spectra showed that the oxygen deficiency in the ZnO lattice reduced with the increase in PEI concentration. Finally, possible mechanisms of the effect of PEI concentration on the ZnO nanorod structure were discussed.