A communications method performed by a network device, the method comprising: • sending first signaling to a first terminal device, wherein the first signaling is used to instruct the first terminal device to perform, on an unlicensed spectrum, a listen before talk, LBT, procedure used for occupying an unlicensed frequency band, and send uplink information within a first time length on the unlicensed frequency band; • receiving, on the unlicensed spectrum, the uplink information from the first terminal device within the first time length, wherein the first time length is a part of a maximum channel occupancy time obtained by the first terminal device on the unlicensed spectrum, and the first time length is less than the maximum channel occupancy time, • sending, after the first time length, first downlink control information within a second time length by using the unlicensed frequency band preempted by the first terminal device to the first terminal device, wherein the unlicensed frequency band preempted by the first terminal device is an unlicensed frequency band on which the uplink information sent by the first terminal device is received, wherein the first downlink control information is used to schedule the first terminal device to receive downlink data within the second time length by using the unlicensed frequency band preempted by the first terminal device, wherein an end time of the first time length is K2, a start time of the second time length is K3, the time K2 and the time K3 are spaced by M1 OFDM symbol lengths, and M1 is an integer greater than 0, wherein the second time length follows the first time length, and a sum of the second time length and the first time length is less than or equal to the maximum channel occupancy time, • sending the downlink data within the second time length by using the unlicensed frequency band to the first terminal device. • sending first signaling to a first terminal device, wherein the first signaling is used to instruct the first terminal device to perform, on an unlicensed spectrum, a listen before talk, LBT, procedure used for occupying an unlicensed frequency band, and send uplink information within a first time length on the unlicensed frequency band; • receiving, on the unlicensed spectrum, the uplink information from the first terminal device within the first time length, wherein the first time length is a part of a maximum channel occupancy time obtained by the first terminal device on the unlicensed spectrum, and the first time length is less than the maximum channel occupancy time, • sending, after the first time length, first downlink control information within a second time length by using the unlicensed frequency band preempted by the first terminal device to the first terminal device, wherein the unlicensed frequency band preempted by the first terminal device is an unlicensed frequency band on which the uplink information sent by the first terminal device is received, wherein the first downlink control information is used to schedule the first terminal device to receive downlink data within the second time length by using the unlicensed frequency band preempted by the first terminal device, wherein an end time of the first time length is K2, a start time of the second time length is K3, the time K2 and the time K3 are spaced by M1 OFDM symbol lengths, and M1 is an integer greater than 0, wherein the second time length follows the first time length, and a sum of the second time length and the first time length is less than or equal to the maximum channel occupancy time, wherein the first downlink control information is used to schedule the first terminal device to receive downlink data within the second time length by using the unlicensed frequency band preempted by the first terminal device, wherein an end time of the first time length is K2, a start time of the second time length is K3, the time K2 and the time K3 are spaced by M1 OFDM symbol lengths, and M1 is an integer greater than 0, wherein the second time length follows the first time length, and a sum of the second time length and the first time length is less than or equal to the maximum channel occupancy time, • sending the downlink data within the second time length by using the unlicensed frequency band to the first terminal device.