A sensing threshold determining method, comprising: measuring, by a sensor node, a target frequency band and determining a used frequency in the target frequency band and received signal strength of the sensor node at the used frequency, wherein the used frequency in the target frequency band comprises a frequency being used or having been used by a primary user transmitter in the target frequency band; characterized in that the method further comprises: determining, by the sensor node, a sensing threshold for an unused frequency in the target frequency band according to the received signal strength at the used frequency, wherein the unused frequency comprises a frequency not used by the primary user transmitter in the target frequency band; wherein the determining, by the sensor node, the sensing threshold for the unused frequency in the target frequency band according to the received signal strength at the used frequency comprises: calculating, by the sensor node, a path loss difference of the primary user transmitter between the used frequency and the unused frequency; and determining, by the sensor node, the sensing threshold for the unused frequency in the target frequency band as a sum of the received signal strength at the used frequency, the path loss difference of the primary user transmitter between the used frequency and the unused frequency, and a transmit power difference of the primary user transmitter between the used frequency and the unused frequency. measuring, by a sensor node, a target frequency band and determining a used frequency in the target frequency band and received signal strength of the sensor node at the used frequency, wherein the used frequency in the target frequency band comprises a frequency being used or having been used by a primary user transmitter in the target frequency band; characterized in that the method further comprises: determining, by the sensor node, a sensing threshold for an unused frequency in the target frequency band according to the received signal strength at the used frequency, wherein the unused frequency comprises a frequency not used by the primary user transmitter in the target frequency band; wherein the determining, by the sensor node, the sensing threshold for the unused frequency in the target frequency band according to the received signal strength at the used frequency comprises: calculating, by the sensor node, a path loss difference of the primary user transmitter between the used frequency and the unused frequency; and determining, by the sensor node, the sensing threshold for the unused frequency in the target frequency band as a sum of the received signal strength at the used frequency, the path loss difference of the primary user transmitter between the used frequency and the unused frequency, and a transmit power difference of the primary user transmitter between the used frequency and the unused frequency. determining, by the sensor node, a sensing threshold for an unused frequency in the target frequency band according to the received signal strength at the used frequency, wherein the unused frequency comprises a frequency not used by the primary user transmitter in the target frequency band; wherein the determining, by the sensor node, the sensing threshold for the unused frequency in the target frequency band according to the received signal strength at the used frequency comprises: calculating, by the sensor node, a path loss difference of the primary user transmitter between the used frequency and the unused frequency; and determining, by the sensor node, the sensing threshold for the unused frequency in the target frequency band as a sum of the received signal strength at the used frequency, the path loss difference of the primary user transmitter between the used frequency and the unused frequency, and a transmit power difference of the primary user transmitter between the used frequency and the unused frequency. calculating, by the sensor node, a path loss difference of the primary user transmitter between the used frequency and the unused frequency; and determining, by the sensor node, the sensing threshold for the unused frequency in the target frequency band as a sum of the received signal strength at the used frequency, the path loss difference of the primary user transmitter between the used frequency and the unused frequency, and a transmit power difference of the primary user transmitter between the used frequency and the unused frequency.