A method of fabricating a thin film transistor array substrate is disclosed. The method includes: sequentially forming a first passivation layer, a photo acryl layer and a first transparent metal layer on the substrate provided with the source/drain electrodes and so on; forming a common electrode, which is disposed in the pixel region, and first through third contact holes, which are positioned in regions of the drain electrode, the gate pad and the data pad, respectively, using one of a half-tone mask and a diffractive mask; forming a second passivation layer on the substrate provided with the first through third contact holes; exposing the drain electrode, the gate pad and the data pad by removing the first and second passivation layers from the drain electrode region, the gate pad region and data pad region; and forming a pixel electrode on the second passivation layer opposite to the common electrode by forming a second transparent metal layer on the substrate and performing a third mask procedure for the second transparent metal layer.