This disclosure provides an array substrate, a method for preparing the array substrate, and a display panel. The method includes: forming a first thin film transistor and a second thin film transistor on a base substrate. In the formation of an active layer of the first thin film transistor, by using an eutectic point of the catalyst particle and silicon, and a driving factor that the Gibbs free energy of amorphous silicon is greater than that of crystalline silicon (silicon-based nanowire), and due to absorption of the amorphous silicon by the molten catalyst particle to form a supersaturated silicon eutectoid, the silicon nucleates and grows into a silicon-based nanowire. Moreover, during the growth of the silicon-based nanowire, the amorphous silicon film grows linearly along guide structure under the action of the catalyst particle, thus obtaining a silicon-based nanowire with a high density and high uniformity. In addition, by controlling the size of the catalyst particle and the thickness of the amorphous silicon film, the width of the silicon-based nanowire may also be controlled. In this way, a thin film transistor having a silicon-based nanowire with a uniform and controllable size is prepared.