A method is provided for fabricating source/drain electrodes of a thin film transistor. The method generally provides a substrate having a first gate electrode and a second gate electrode adjacent and electrically connected. The method further provides coating a photoresist layer on the metal layer, and performing an exposure process on the photoresist layer by a photomask. The method further performs a development process on the exposed photoresist layer to form a photoresist pattern layer with different thicknesses on the metal layer, and then etches the metal layer using the photoresist pattern layer as an etch mask, to form a pair of first source/drain electrodes on the first gate electrode and a pair of second source/drain electrodes on the second gate electrode.