A communication system includes a first network device and a second network device. A power consumption control method applied to the communication system includes the steps of: checking a receiving capability of the first network device to generate a first checking result; and selectively notifying the second network device to adjust a transmitting capability of the second network device according to the first checking result. When the first checking result indicates that the receiving capability of the first network device is greater than a first threshold, transmit a first notice signal to notify the second network device. When receiving the first notice signal, lower the transmitting capability of the second network device.