Abstract: A fabrication method of a polysilicon layer is provided. First, a substrate is provided. Then, an amorphous silicon layer is formed on the substrate. After that, a patterned photomask having a light transmitting area and a light shielding area is provided, and the amorphous silicon layer is irradiated with a light by using the patterned photomask as a mask, wherein the amorphous silicon layer corresponding to the light transmitting area is transformed into a hydrophilic amorphous silicon layer, and the amorphous silicon layer corresponding to the light shielding area remains as a hydrophobic amorphous silicon layer. Next, a hydrophilic metal catalyst is provided and disposed on the hydrophilic amorphous silicon layer. After that, an annealing process is performed to transform the hydrophilic metal catalyst into a metal catalyst layer, and the metal catalyst layer reacts with the amorphous silicon layer to form a polysilicon layer.