The disclosure provides a thin film transistor, a manufacturing method thereof, a display substrate and a display apparatus. The thin film transistor comprises a base substrate, and an active layer disposed on the base substrate, and the active layer comprises a channel region, and a source contact region and a drain contact region respectively positioned at two sides of the channel region; and a portion of at least one of the source contact region and the drain contact region close to the channel region includes a plurality of first sub-grooves disposed at a side of the active layer proximal to the base substrate and a plurality of second sub-grooves disposed at a side of the active layer distal to the base substrate, and the plurality of first sub-grooves and the plurality of second sub-grooves being alternately disposed along a direction parallel to an extension of the channel region.