A TFT array substrate and its manufacturing method are disclosed. The TFT array substrate includes a substrate having a display area and a non-display area, and at least a Schottky diode on the non-display area. The Schottky diode includes an anode layer and a cathode layer on the substrate, a gate insulation layer on the substrate covering the anode and cathode layers, a first gate on the gate insulation layer covering portions of the anode and cathode layers, an inter-layer insulation layer on the gate insulation layer covering the first gate and having a number of vias exposing the anode and cathode layers, respectively, and a first electrode and a second electrode in the vias on the inter-layer insulation layer connecting the anode and cathode layers, respectively. The present disclosure achieves simplified manufacturing process and reduced cost by forming the Schottky diode simultaneously when the TFT is formed.