A method for controlling a transmission rate of a communication interface includes detecting, for a plurality of times, data traffic that passes through a first communication interface of a first device within a preset period; when the traffic rates at which the data traffic passes through the first communication interface within the preset period are lower than a first threshold, sending a rate reduction request message to a second device that includes a second communication interface, so that the second device configures a rate of the second communication interface as a first transmission rate that is lower than a current transmission rate of the second communication interface and that is supported by both communication interfaces after receiving the rate reduction request message. In this way, power consumption of the communication interface may be reduced.