A method of making a thin film transistor, the method including: providing an insulating layer on a semiconductor substrate, forming a semiconductor layer on the insulating layer; locating a first photoresist layer, a nanowire structure, a second photoresist layer on the semiconductor layer, wherein the nanowire structure comprises a nanowire; forming an opening in the first photoresist layer and the second photoresist layer to form an exposed surface, wherein a part of the nanowire is exposed in the opening; depositing a conductive film layer on the exposed surface of the semiconductor layer, wherein the conductive film layer defines a nano-scaled channel corresponding to the nanowire, and the conductive film layer is divided into two regions by the nano-scaled channel, one region is used as a source electrode, and the other region is used as a drain electrode; forming a gate electrode on the semiconductor substrate.