The invention provides a thin film transistor, an array substrate, a manufacturing method of the thin film transistor and the array substrate and a display device, and belongs to the technical field of display. The manufacturing method of the thin film transistor comprises the steps that a substrate base plate is provided; a grid is formed on the substrate base plate, wherein at least part of thearea of the grid is made of a transparent conductive material; a gate insulating layer covering the gate is formed; an amorphous silicon pattern is formed on the gate insulating layer, wherein an orthographic projection of the at least part of the area on the substrate base plate coincides with at least part of the orthographic projection of the amorphous silicon pattern on the substrate base plate; and laser annealing treatment is simultaneously carried out on the amorphous silicon pattern from the side, facing away from the substrate base plate, of the amorphous silicon pattern and from theside, facing away from the amorphous silicon pattern, of the substrate base plate. According to the technical scheme of the thin film transistor, the array substrate, the manufacturing method of the thin film transistor and the array substrate and the display device, the crystallization speed for forming polycrystalline silicon can be accelerated during the manufacturing process of the polycrystalline silicon thin film transistor, and the production efficiency of the polycrystalline silicon thin film transistor is improved.