The present invention discloses a thin-film transistor and a fabricating method thereof, an array substrate and a display apparatus. An active layer in the thin-film transistor comprises a first active layer and a second active layer which are stacked; wherein, an orthographic projection of the first active layer on the substrate covers orthographic projections of the source electrode, the drain electrode as well as a gap located between the source electrode and the drain electrode on the substrate, and covers an orthographic projection of the gate electrode on the substrate; the second active layer is located at the gap between the source electrode and the drain electrode, and an orthographic projection of the second active layer on the substrate is located in a region where the orthographic projection of the gate electrode on the substrate is located.