The disclosure relates to a thin film transistor and a method for making the same. The thin film transistor includes a substrate; a semiconductor layer on the substrate, wherein the semiconductor layer includes nano-scaled semiconductor materials; a source and a drain, wherein the source and the drain are on the substrate, spaced apart from each other, and electrically connected to the semiconductor layer; a dielectric layer on the semiconductor layer, wherein the dielectric layer includes a first sub-dielectric layer and a second sub-dielectric layer stacked on one another, and the first sub-dielectric layer is a first oxide dielectric layer grown by magnetron sputtering; and a gate in direct contact with the first sub-dielectric layer. The thin film transistor almost has no current hysteresis.