1. An intelligent entrance guard unlocking system comprising: a power unit of an intelligent entrance guard; a current transmitter of the intelligent entrance guard electrically coupling the power unit with a transmitter coil, and configured to receive electric energy supplied by the power unit, wherein the current transmitter transmits the electric energy by wireless electromagnetic radiation via the transmit coil; a first storage unit of the intelligent entrance guard storing a predefined iris image; a first controller of the intelligent entrance guard coupled to the first storage unit; a wireless receiver unit of the intelligent entrance guard coupled to the first controller; an unlocking unit of the intelligent entrance guard coupled to the first controller; and a powerless smart key 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 directly by the received electric energy and then the powerless smart key works; an iris recognition unit coupled to a second storage unit, and configured to scan an eye of a user to recognize an iris image of the user and further store the iris image in the second storage unit; 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 iris image; a current convertor electrically coupling the current receiver with the second controller; and a first current-stabilizing unit electrically coupling the current receiver with the current convertor, and configured to stabilize current of the received electric energy to prevent the current to exceed a predefined value suddenly; wherein the wireless receiver unit receives the wireless signal, the first controller is configured to obtain the predefined iris image from the first storage unit and compare the iris image with the predefined iris image, and the unlocking unit is configured to unlock the intelligent entrance guard when the iris image matches with the predefined iris image, and not unlock the intelligent entrance guard when the iris image does not match with the predefined iris image.