The ZnO nanowire-based insulation gate field effect transistors were fabricated by connecting single ZnO nanowires across three kinds of symmetrical metal trenches (Au, Zn and Al thin films) with different widths. In the testing processes, the traditional ion beam eroding technology, electronic probe, and atom force microscopy probe methods were employed. The I-V characteristics of various synthesized ZnO nanowire-based devices were researched. The results showed that the main effecting factor on the I-V characteristic is the type of contact between the ZnO nanowire and the surface of different trenches, which may be of the Ohmic or the Schottky contact type in different cases. Finally, the I-V characteristics of the fabricated devices had been discussed by using the electron transport mechanism.