Thin film transistor array substrate and liquid crystal display device

The invention discloses a thin film transistor array substrate. The thin film transistor array substrate comprises a substrate; a first metal layer, which is formed on the substrate and connected with a corresponding scanning line; a first insulation protecting layer, which is formed on the substrate; a semiconductor layer, which is formed on the first insulation protecting layer; a pixel electrode, which is formed on the first insulation protecting layer and located at every pixel zone; a second metal layer, which is formed on the semiconductor layer, and includes a source electrode and a drain electrode, wherein the source electrode is connected with corresponding data line, and the drain electrode is connected with the corresponding pixel electrode; the second insulation protecting layer forms on the second metal layer, and covers every data line and every scanning line; a third insulation protecting layer, which forms on the second insulation protecting layer; a public electrode, which forms on the third insulation protecting layer. The thin film transistor array substrate can improve the penetration rate, decrease load and reduce power consumption. The invention further relates to a liquid crystal display device.