A high-sensitivity self-capacitance in-cell touch display panel device includes a sensing electrode layer having plural sensing electrodes, a display control circuit, a touch sensing control circuit, and an amplifier with gain greater than zero. The display control circuit is powered by a first power source and connected to a first ground. The touch sensing control circuit is coupled to the sensing electrodes for performing a touch sensing. The touch sensing control circuit is powered by a second power source and connected to a second ground, wherein the first power source and the first ground are different from the second power source and the second ground. The amplifier is connected to the touch sensing control circuit and a common voltage layer. The touch sensing control circuit applies a sensing signal sensed by at least one sensing electrode to the amplifier for being amplified and applied to the common voltage layer.