A TFT array substrate is provided. The TFT array substrate includes a substrate, a patterned first metallic layer, a patterned semiconductor layer, a patterned transparent conductive layer, a patterned dielectric layer, and a patterned second metallic layer. Elements of each TFT of the TFT array substrate are arranged vertically, so that the TFT array substrate has relatively small fabrication area and is operable with a high conducting current. Further, the storage capacitance can be enhanced by enclosing or sandwiching the transparent electrodes with the common lines and the second metallic layer, or alternatively by enclosing or sandwiching the second metallic layer with the common lines and the transparent electrodes.