A frequency calibration method for an electronic device, wherein the frequency calibration method comprises: transmitting a first request packet to a time server at a device first time instant; receiving a first response packet responding the first request packet from the time server at a device second time instant; transmitting a second request packet to the time server at a device third time instant, wherein a device first time interval (X') is equal to a difference between the device first time instant and the device third time instant; receiving a second response packet responding the second request packet from the time server at a device fourth time instant, wherein a device second time interval (Y') is equal to a difference between the device second time instant and the device fourth time instant; and calibrating a clock frequency of the electronic device according to the first response packet, the second response packet, and at least one of the device first time interval (X') and the device second time interval (Y'), characterized in that the frequency calibration method further comprises: calculating a first round trip delay, RTD1, between transmitting the first request packet and receiving the first response packet; calculating a second round trip delay, RTD2, between transmitting the second request packet and receiving the second response packet; and when a difference between the first round trip delay, RTD1, and the second round trip delay, RTD2, is greater than a threshold value, Th, retransmitting the second request packet to the time server after waiting a retransmission time interval, Tr. transmitting a first request packet to a time server at a device first time instant; receiving a first response packet responding the first request packet from the time server at a device second time instant; transmitting a second request packet to the time server at a device third time instant, wherein a device first time interval (X') is equal to a difference between the device first time instant and the device third time instant; receiving a second response packet responding the second request packet from the time server at a device fourth time instant, wherein a device second time interval (Y') is equal to a difference between the device second time instant and the device fourth time instant; and calibrating a clock frequency of the electronic device according to the first response packet, the second response packet, and at least one of the device first time interval (X') and the device second time interval (Y'), characterized in that the frequency calibration method further comprises: calculating a first round trip delay, RTD1, between transmitting the first request packet and receiving the first response packet; calculating a second round trip delay, RTD2, between transmitting the second request packet and receiving the second response packet; and when a difference between the first round trip delay, RTD1, and the second round trip delay, RTD2, is greater than a threshold value, Th, retransmitting the second request packet to the time server after waiting a retransmission time interval, Tr. calculating a first round trip delay, RTD1, between transmitting the first request packet and receiving the first response packet; calculating a second round trip delay, RTD2, between transmitting the second request packet and receiving the second response packet; and when a difference between the first round trip delay, RTD1, and the second round trip delay, RTD2, is greater than a threshold value, Th, retransmitting the second request packet to the time server after waiting a retransmission time interval, Tr.