A simple route of external mechanical force is presented for enhancing the electrical properties of polymer nanocomposite consisted of nanowires. By dispersing ZnO nanowires in polymer solution and drop casting on substrates, nanocomposite transistors containing ZnO nanowires are successfully fabricated. Even though the ZnO nanowires density is properly controlled for device fabrication, as-casted device does not show any detectable currents, because nanowires are separated far from each other with the insulating polymer matrix intervening between them. Compared to the device pressed at 300 kPa, the device pressed at 600 kPa exhibits a significantly enhanced performance. Such an improved device performance would be realized by the contacts improvement and the increase of the number of electrical path induced by external force. This approach provides a viable solution for serious contact resistance problem of nanocomposite materials and broadens their use in a variety of applications.