A wireless charging apparatus, comprising: a voltage converting circuit, configured to receive an input voltage and convert the input voltage to obtain an output voltage and an output current of the voltage converting circuit; a wireless transmitting circuit, configured to transmit an electromagnetic signal according to the output voltage and the output current of the voltage converting circuit to conduct wireless charging on a device to-be-charged; and a first control circuit, configured for wireless communication with the device to-be-charged during the wireless charging to acquire at least one of an output voltage and an output current of a step-down circuit fed back by the device to-be-charged, and adjust at least one of the output voltage and the output current of the voltage converting circuit according to at least one of the output voltage and the output current of the step-down circuit to adjust a transmission power of the electromagnetic signal, to make a voltage difference between an input voltage of the step-down circuit and the output voltage of the step-down circuit meet a preset condition; wherein the wireless charging apparatus is characterized in that: the first control circuit is configured to roughly adjust the output voltage of the voltage converting circuit to a first voltage, according to the output voltage of the step-down circuit fed back by the device to-be-charged and a preset correspondence relationship between voltage differences and charging efficiencies, wherein the preset correspondence relationship is determined according to working characteristics of the step-down circuit, and to further finely adjust the output voltage of the voltage converting circuit to a second voltage, after the output voltage being adjusted to the first voltage, according to the output current of the step-down circuit fed back by the device to-be-charged and a preset threshold current. a voltage converting circuit, configured to receive an input voltage and convert the input voltage to obtain an output voltage and an output current of the voltage converting circuit; a wireless transmitting circuit, configured to transmit an electromagnetic signal according to the output voltage and the output current of the voltage converting circuit to conduct wireless charging on a device to-be-charged; and a first control circuit, configured for wireless communication with the device to-be-charged during the wireless charging to acquire at least one of an output voltage and an output current of a step-down circuit fed back by the device to-be-charged, and adjust at least one of the output voltage and the output current of the voltage converting circuit according to at least one of the output voltage and the output current of the step-down circuit to adjust a transmission power of the electromagnetic signal, to make a voltage difference between an input voltage of the step-down circuit and the output voltage of the step-down circuit meet a preset condition; wherein the wireless charging apparatus is characterized in that: the first control circuit is configured to roughly adjust the output voltage of the voltage converting circuit to a first voltage, according to the output voltage of the step-down circuit fed back by the device to-be-charged and a preset correspondence relationship between voltage differences and charging efficiencies, wherein the preset correspondence relationship is determined according to working characteristics of the step-down circuit, and to further finely adjust the output voltage of the voltage converting circuit to a second voltage, after the output voltage being adjusted to the first voltage, according to the output current of the step-down circuit fed back by the device to-be-charged and a preset threshold current.