The present disclosure discloses a thin film transistor and a manufacturing method thereof, an array substrate and a display device, and belongs to the field of semiconductor display technology. The active layer of the thin film transistor is made of a CIGS material. By manufacturing the active layer of the thin film transistor with the CIGS material, and the crystal defects of the CIGS are less than LTPS and IGZO, the mobility of the thin film transistor is higher, and the switching speed of the thin film transistor is faster, thereby being advantageous to further improve the resolution of the display device.