A method for using an unlicensed spectrum, comprising: sending, by a network device, a measurement configuration to at least two terminal devices, wherein the measurement configuration configures each terminal device to measure a to-be-measured unlicensed frequency band and report a measurement result of the to-be-measured unlicensed frequency band; receiving, by the network device, at least two measurement reports from the at least two terminal devices, wherein a measurement report from a terminal device comprises a measurement result of the to-be-measured unlicensed frequency band, and the measurement result of each to-be-measured unlicensed frequency band comprises any one or more of the following information about the to-be-measured unlicensed frequency band: RSRP, RSRQ, and an SINR; obtaining (S301, S3014), by a network device, based on the at least two measurement reports from the at least two terminal devices information about a target unlicensed frequency band, wherein the information about the target unlicensed frequency band comprises one of or a combination of more than one of the following information: reference signal received power RSRP, reference signal received quality RSRQ, and a signal to interference plus noise ratio SINR, wherein obtaining the information about the target unlicensed frequency band comprises obtaining based on a plurality of measurement results in the at least two measurement reports, information about one or more unlicensed frequency bands, and wherein the target unlicensed frequency band meets any one or more of the following first conditions: the RSRP is less than or equal to a first threshold, the RSRQ is less than or equal to a second threshold, and the SINR is less than or equal to a third threshold; and transmitting, by the network device,, based on the information about the target unlicensed frequency band, a signal on a supplementary uplink SUL, wherein a spectrum of the SUL comprises the target unlicensed frequency band. sending, by a network device, a measurement configuration to at least two terminal devices, wherein the measurement configuration configures each terminal device to measure a to-be-measured unlicensed frequency band and report a measurement result of the to-be-measured unlicensed frequency band; receiving, by the network device, at least two measurement reports from the at least two terminal devices, wherein a measurement report from a terminal device comprises a measurement result of the to-be-measured unlicensed frequency band, and the measurement result of each to-be-measured unlicensed frequency band comprises any one or more of the following information about the to-be-measured unlicensed frequency band: RSRP, RSRQ, and an SINR; obtaining (S301, S3014), by a network device, based on the at least two measurement reports from the at least two terminal devices information about a target unlicensed frequency band, wherein the information about the target unlicensed frequency band comprises one of or a combination of more than one of the following information: reference signal received power RSRP, reference signal received quality RSRQ, and a signal to interference plus noise ratio SINR, wherein obtaining the information about the target unlicensed frequency band comprises obtaining based on a plurality of measurement results in the at least two measurement reports, information about one or more unlicensed frequency bands, and wherein the target unlicensed frequency band meets any one or more of the following first conditions: the RSRP is less than or equal to a first threshold, the RSRQ is less than or equal to a second threshold, and the SINR is less than or equal to a third threshold; and transmitting, by the network device,, based on the information about the target unlicensed frequency band, a signal on a supplementary uplink SUL, wherein a spectrum of the SUL comprises the target unlicensed frequency band.