Abstract: Embodiments of the present disclosure provide a thin-film transistor (TFT), an array substrate and a manufacturing method thereof, and a display device. The method for preparing a TFT according to an embodiment of the present disclosure may comprise: providing a base substrate; and forming an active layer and an insulation layer on the base substrate. The active layer and the insulation layer may be arranged sequentially and in contact with each other, and the insulation layer may include at least one first insulation layer one of which is in contact with the active layer. The step of forming the first insulation layer may comprise: forming a first insulation film; and conducting a repairing process on the first insulation film by using a repairing source which provides filling atoms, so as to form bonds between at least part of dangling bonds in the first insulation film and the filling atoms.