A gap determining method and a device are provided. The 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, where the scheduling information is used to schedule N transport blocks carried on a first channel. 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, where the preset condition includes that the first gap includes the gap part that overlaps 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 that is included in the first gap and that overlaps with the downlink gap belongs to the downlink gap.