The present invention provides a thin film transistor array substrate and a liquid crystal display panel. The thin film transistor array substrate comprises: a substrate; a light shielding layer, located at a middle part on a surface of the substrate; a buffer layer, covering the light shielding layer; a Low Temperature Poly-silicon layer, being located on the buffer layer, and corresponding to the light shielding layer; an isolation layer, covering the Low Temperature Poly-silicon layer, and the isolation layer comprises a through hole, wherein a width of the through hole is smaller than a width of the light shielding layer; a metal layer, located on the isolation layer, and the metal layer is connected with the Low Temperature Poly-silicon layer via the through hole. The thin film transistor array substrate and the liquid crystal display panel have a higher aperture ratio.