1. An intelligent entrance guard unlocking system comprising: a power unit configured to supply electric power; a current transmitter electrically coupling the power unit to a transmit coil, the current transmitter configured to receive electric energy supplied by the power unit and transmit the electric energy in a way of wireless electromagnetic radiation via the transmit coil; a first controller coupled to the power unit; a first storage unit coupled to the first controller, and configured for storing a predefined face image; a wireless receiver unit coupled to the first controller; an unlocking unit coupled to the first controller; and a powerless smart key coupled to the wireless receiver unit, comprising: a receiver coil; a current receiver electrically coupled to the receiver coil and configured to receive the electric energy via the receiver coil such that the powerless smart key is powered; a face capturing unit coupled to a second storage unit and configured to obtain a face image of the user and further store the face image in the second storage unit; and a second controller coupled to a wireless transmit unit with the second storage unit and configured to control the wireless transmit unit to transmit a wireless signal containing the face image to the intelligent entrance guard; and wherein the wireless receiver unit receives the wireless signal; the first controller is configured to compare the face image with the predefined face image; and the unlocking unit is configured to unlock when the face image matches with the predefined face image.