A method for manufacturing a panel of a thin film transistor liquid crystal display device with three mask processes is disclosed. The method includes following steps: forming a transparent conductive layer, a first insulating layer, and a second metal layer on a transparent substrate in sequence; forming a source area, a drain area, a transparent electrode area, and data signal lines through a halftone photolithography and an etching; forming a semiconducting layer and a second insulating layer on the substrate in sequence; forming a semiconducting channel area in a thin film transistor area and contacts on the source area, the drain area, and the data signal lines through a photolithography and an etching; forming a third metal layer and a third insulating layer on the substrate in sequence; forming scanning signal lines and gate lines through a photolithography and an etching.