A gap determining method includes: A terminal device receives first configuration information and second configuration information from a network device. The terminal device receives scheduling information from the network device. The terminal device determines a downlink gap of the first channel based on the first configuration information. The terminal device determines a first gap between the N transport blocks based on the second configuration information. When the terminal device determines that a preset condition is satisfied, the terminal device determines that a gap part that is included in the first gap and that overlaps with the downlink gap is postponed in time domain and that a gap part obtained through postponing does not overlap with the downlink gap; or when the first gap includes a gap part that overlaps with the downlink gap, the terminal device determines that the gap part belongs to the downlink gap.