An energy detection method, comprising: controlling a driving current of a communication device to be equal to a first current value during a first time interval; intermittently turning on and turning off a first part of receiving functions of the communication device during a second time interval, wherein the second time interval is after the first time interval, and when the first part of receiving functions of the communication device is turned on, the first part of receiving functions of the communication device is controlled to receive a beacon signal and determine whether energy of a signal received by the communication device is greater than or equal to a threshold, wherein the driving current of the communication device is equal to a second current value when the first part of receiving functions of the communication device is turned on during the second time interval, and the second current value is greater than the first current value; when determining the energy of the signal received by the communication device is smaller than the threshold, turning off the first part of receiving functions of the communication device, wherein the driving current of the communication device is equal to a third current value when the first part of receiving functions of the communication device is turned off during the second time interval, and the third current value is less than the second current value and greater than the first current value; when the energy of the signal received by the communication device is greater than or equal to the threshold and when an offset of the energy is smaller than a tolerance value, determining the beacon signal is present and performing a link stage process of the communication device for turning on a second part including all receiving functions of the communication device in order to receive complete content of the beacon signal, wherein the driving current of the communication device is equal to a fourth current value when the second part including all receiving functions of the communication device is turned on, and the fourth current value is greater than the second current value; and when the offset of the energy is greater than the tolerance value, continuing intermittently turning on and turning off the first part of receiving functions of the communication device. controlling a driving current of a communication device to be equal to a first current value during a first time interval; intermittently turning on and turning off a first part of receiving functions of the communication device during a second time interval, wherein the second time interval is after the first time interval, and when the first part of receiving functions of the communication device is turned on, the first part of receiving functions of the communication device is controlled to receive a beacon signal and determine whether energy of a signal received by the communication device is greater than or equal to a threshold, wherein the driving current of the communication device is equal to a second current value when the first part of receiving functions of the communication device is turned on during the second time interval, and the second current value is greater than the first current value; when determining the energy of the signal received by the communication device is smaller than the threshold, turning off the first part of receiving functions of the communication device, wherein the driving current of the communication device is equal to a third current value when the first part of receiving functions of the communication device is turned off during the second time interval, and the third current value is less than the second current value and greater than the first current value; when the energy of the signal received by the communication device is greater than or equal to the threshold and when an offset of the energy is smaller than a tolerance value, determining the beacon signal is present and performing a link stage process of the communication device for turning on a second part including all receiving functions of the communication device in order to receive complete content of the beacon signal, wherein the driving current of the communication device is equal to a fourth current value when the second part including all receiving functions of the communication device is turned on, and the fourth current value is greater than the second current value; and when the offset of the energy is greater than the tolerance value, continuing intermittently turning on and turning off the first part of receiving functions of the communication device.