A method for fabricating a metal-oxide semiconductor (MOS) transistor is disclosed. The method includes the steps of: providing a semiconductor substrate; forming a silicon layer on the semiconductor substrate; performing a first photo-etching process on the silicon layer for forming a gate pattern; forming an epitaxial layer in the semiconductor substrate adjacent to two sides of the gate pattern; and performing a second photo-etching process on the gate pattern to form a slot in the gate pattern while using the gate pattern to physically separate the gate pattern into two gates.