A data reading device that transmits power to a data transmission device and reads data transmitted from the data transmission device is provided. The data reading device includes: a first electrode, forming a first coupling capacitance with the data transmission device; a second electrode, forming a second coupling capacitance with the data transmission device; a control circuit, coupled to the first electrode and the second electrode, configured to provide the first electrode with a first reference voltage and the second electrode with a second reference voltage to cause a voltage difference between the first electrode and the second electrode to vary with time, and to detect charge changes of the first coupling capacitance and the second capacitor; and a determination unit, coupled to the control circuit, configured to determine the data according to the charge changes.