The disclosure provides a touch display panel. A scan line enters a display mode and a touch mode in a scan period. In the display mode, the scan line receives a first voltage to turn off a switch unit and enable a pixel unit to receive a pixel voltage signal from a first signal transmission line; and in the touch mode, the scan line receives a second voltage to turn on the switch unit and disable the corresponding pixel unit to stop receiving the pixel voltage signal, such that a sensing pixel unit outputs a touch sensing signal to the first signal transmission line through the switch unit, wherein the first voltage is greater than the second voltage. In the disclosure, an aperture ratio of the touch display panel is improved efficiently to meet the requirement of narrow border design of the touch display panel.