A TFT array substrate includes a substrate, a patterned first metallic layer, a patterned stack layer, a patterned dielectric layer, a patterned transparent conductive layer, and a patterned third metallic layer. Elements of each TFT in 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 second metallic layer with the common lines and the transparent electrodes. In such a way, pixel flashing caused by those coupled signals can be reduced, thus promoting displaying quality thereof.