Making method of thin film transistor array substrate

The invention provides a making method of a thin film transistor array substrate, which comprises the steps of proving a substrate defined with at least one thin film transistor region and a peripheral circuit region; forming a patterned gate layer, a first dielectric layer, a second dielectric layer and a semiconductor layer in sequence on the substrate; removing a part of the semiconductor layer, forming a patterned semiconductor layer in the thin film transistor region, and removing the second dielectric layer which is not covered by the patterned semiconductor layer; forming a source electrode and a drain electrode on the patterned semiconductor layer in the thin film transistor region; forming an insulating layer on the substrate; and removing a part of the insulating layer and the first dielectric layer and forming a first contact hole and a second contact hole respectively in the thin film transistor region and the peripheral circuit region.