A method for manufacturing a substrate of a TFT LCD device is disclosed with following steps: providing a transparent substrate having a thin film transistors area and a storing capacitor area; forming an aluminum metal layer and a metal protecting layer on the substrate; patterning a first pattern on the aluminum metal layer of the TFT area, and a second pattern on the metal protecting layer of the storing capacitor area through a halftone mask; forming an aluminum nitride layer on the patterned metal protecting layer; removing the aluminum nitride layer form a rugged surface; forming patterned gates, patterned sources, and patterned drains over the patterned metal protecting layer of the TFT area, and forming a second metal layer over the rugged surface of the aluminum layer on the storing capacitor area, wherein the second metal layer is electrically connected with the drains; and forming patterned pixel electrodes.