A method for fabricating a thin film transistor array substrate is provided. Wherein, a plurality of contact holes and recesses are formed in a protection layer disposed upon thin film transistors. Each recess comprises an under-cut profile while each contact hole exposes a drain-metal layer of a corresponding thin film transistor. Then, a transparent conductor layer is formed on the protection layer, which in turn fills in the contact holes so as to be electrically connected to the drain-metal layer. Besides, the transparent conductor layer automatically segregates at the recesses to form a plurality of pixel electrodes, whereby the plurality of pixel electrodes can be formed without the utilization of photolithography and etching processes and thus fabricating cost is lowered.