Back-gate field effect transistors based on In-doped ZnO individual nanobelts have been fabricated using the low-cost microgrid template method. The output (Ids-Vds) and transfer (Ids-Vgs) characteristic curves for the transistors are measured, and the mobility is derived to be 622 cm2· V-1· s-1. This value is obviously superior to those for most of materials including pure ZnO in the literature, and possible influence factors have also been discussed.