A manufacturing method of a thin film transistor array substrate incorporating the manufacture of a photo-sensor is provided. In the manufacturing method, a photo-sensing dielectric layer is formed between a transparent conductive layer and a metal electrode for detecting ambient light. Since the transparent conductive layer is adopted as an electrode, the ambient light can pass through the transparent conductive layer and get incident light into the photo-sensing dielectric layer. Therefore, the sensing area of the photo-sensor can be enlarged and the photo-sensing efficiency is improved. In addition, the other side of the photo sensitive dielectric layer may be a metal electrode. The metal electrode can block the backlight from getting incident into the photo-sensing dielectric layer and thus reduce the background noise. A manufacturing method of a liquid crystal display panel adopting the aforementioned thin film transistor array substrate is also provided.