The present application provides a thin film transistor, an active matrix organic light emitting diode assembly and a method for manufacturing the same. The thin film transistor includes: a substrate; a buffer layer on the substrate; a semiconductor layer on the buffer layer, including a source region, a drain region and a channel region; a first gate insulating layer covering the semiconductor layer; a second gate insulating layer foot on the first gate insulating layer, a width of the second gate insulating layer foot being smaller than a width of the first gate insulating layer; and a gate electrode on the second gate insulating layer foot; wherein a part of the first gate insulating layer that is on the semiconductor layer has a flat upper surface. The present application may obtain better implantation profiles of source region and drain region, thereby obtaining better uniformity in TFT performance.