A method for reducing power consumption of a communications device, wherein the method comprises: determining a minimum supply voltage that is for a WiFi power amplification circuit at an actual transmit power and that meets a WiFi communication rate; and providing a working voltage to the WiFi power amplification circuit to transmit data, wherein the working voltage is a voltage that is not lower than the minimum supply voltage and that is lower than a maximum supply voltage; wherein the determining a minimum supply voltage that is for a WiFi power amplification circuit at an actual transmit power and that meets a WiFi communication rate comprises: searching a voltage mapping table for the minimum supply voltage corresponding to the WiFi communication rate and the actual transmit power, wherein the voltage mapping table records a one-to-one mapping relationship among the WiFi communication rate, a maximum transmit power, and the minimum supply voltage, each WiFi communication rate is corresponding to at least two different maximum transmit powers, the at least two different maximum transmit powers are separately corresponding to different minimum supply voltages, the maximum transmit power is a maximum transmit power that is defined by a WiFi communications protocol and that can be implemented at the minimum supply voltage and the WiFi communication rate, and searching for the corresponding actual transmit power in the voltage mapping table is searching for the maximum transmit power same as the actual transmit power. determining a minimum supply voltage that is for a WiFi power amplification circuit at an actual transmit power and that meets a WiFi communication rate; and providing a working voltage to the WiFi power amplification circuit to transmit data, wherein the working voltage is a voltage that is not lower than the minimum supply voltage and that is lower than a maximum supply voltage; wherein the determining a minimum supply voltage that is for a WiFi power amplification circuit at an actual transmit power and that meets a WiFi communication rate comprises: searching a voltage mapping table for the minimum supply voltage corresponding to the WiFi communication rate and the actual transmit power, wherein the voltage mapping table records a one-to-one mapping relationship among the WiFi communication rate, a maximum transmit power, and the minimum supply voltage, each WiFi communication rate is corresponding to at least two different maximum transmit powers, the at least two different maximum transmit powers are separately corresponding to different minimum supply voltages, the maximum transmit power is a maximum transmit power that is defined by a WiFi communications protocol and that can be implemented at the minimum supply voltage and the WiFi communication rate, and searching for the corresponding actual transmit power in the voltage mapping table is searching for the maximum transmit power same as the actual transmit power. searching a voltage mapping table for the minimum supply voltage corresponding to the WiFi communication rate and the actual transmit power, wherein the voltage mapping table records a one-to-one mapping relationship among the WiFi communication rate, a maximum transmit power, and the minimum supply voltage, each WiFi communication rate is corresponding to at least two different maximum transmit powers, the at least two different maximum transmit powers are separately corresponding to different minimum supply voltages, the maximum transmit power is a maximum transmit power that is defined by a WiFi communications protocol and that can be implemented at the minimum supply voltage and the WiFi communication rate, and searching for the corresponding actual transmit power in the voltage mapping table is searching for the maximum transmit power same as the actual transmit power.