Provided is a thin film transistor, including: a conductive light shielding layer; a metal oxide layer arranged on the light shielding layer; a buffer layer, an active layer, a gate insulating layer, a gate electrode, and an interlayer insulating layer arranged in sequence on the metal oxide layer, the interlayer insulating layer and the buffer layer comprising a first via hole and a second via hole for exposing the active layer, and a third via hole for exposing the metal oxide layer, in which a portion of the metal oxide layer exposed through the third via hole is a conductive portion, and other portions are insulative; and a source electrode and a drain electrode arranged on the interlayer insulating layer, in which the source electrode is connected to the active layer through the first via hole, and the drain electrode is connected to the active layer through the second via hole and connected to the conductive portion through the third via hole.