In this work the piezoelectric effect of one-dimensional ZnO gear-shaped microwires (GMWs) is studied by the finite element method. By calculating the piezopotential of substrate-bound gear-shaped ZnO microwires oriented along the c-axis with gear groove depth of 0-5 mu m, we demonstrate that the GMW has more advantage for piezoelectric nanogenerators than the common hexagonal microwire (HMW). To understand the anisotropic electricity generation, the calculated piezopotential distribution in the bent ZnO GMW and HMW has been analyzed under an external force with the different directions. Moreover, the calculation also indicates that the effect of geometric size on piezopotential for the GMW is similar to the HMW. Our results will be a guidance for the design of high-efficiency energy harvesting devices. (C) 2014 Elsevier B.V. All rights reserved.