A wireless display device includes an antenna unit, a processing unit, a display unit, and a power supply unit. The antenna unit is provided for receiving a first electromagnetic wave and a third electromagnetic wave, and transmitting a second electromagnetic wave. The processing unit is connected to the antenna unit for obtaining an identification data, a display data and a first electric power from the first electromagnetic wave, and the first electric power provides power for the processing unit. Additionally, the display unit is connected to the processing unit for displaying an image in accordance with the display data via the processing unit. The power supply unit is connected to the antenna unit and the display unit for obtaining a second electric power from the third electromagnetic wave so as to provide the display unit with the second electric power.