Using density functional theory combined with nonequilibrium Green's function formalism, we investigate the transport properties of zigzag graphene nanoribbons (ZGNRs) under vertical strain. Our calculations show that localized state induced by vertical strain will inhibit the electronic transport of the systems at zero bias, but at nonzero bias, the localized state can enhance the electronic transport behavior if ZGNRs are symmetry with respect to the mid-plane between two edges. This is because the localized state produces an asymmetry electron density distribution which break the current suppression. These findings may be useful for the application of strain-induced ZGNR based molecular devices. (C) 2017 Elsevier B.V. All rights reserved.