The invention provides a thin film transistor, an array substrate, a display panel and a display device, and relates to the technical field of display. The thin film transistor comprises a grid electrode, a grid insulation layer, a source electrode, a drain electrode and an active layer located on a substrate. The thin film transistor is characterized in that the projection of the grid electrode on the substrate and the projection of the active layer on the substrate have a plurality of independent overlapped areas. According to the scheme, the grid electrode and the active layer of the thin film transistor have the multiple independent overlapped areas, one thin film transistor structure equivalently forms a plurality switches in principle, due to the design, leak current of the thin film transistor can be effectively lowered, meanwhile, influences caused by the leak current on the performance of the thin film transistor can be reduced, and therefore the poor phenomenon that a display frame of a display product shakes can be improved when the thin film transistor is applied to the display product.