A communications method includes: obtaining first indication information and format information; and determining, based on a transmission direction that is of a sub-time unit in a time unit and that is indicated by the first indication information and a transmission direction that is of the sub-time unit and that is indicated by the format information, whether the time unit is an aggregation time unit. It is determined, based on the transmission direction that is of the sub-time unit in the time unit and that is configured in the first indication information and the transmission direction that is of the sub-time unit and that is configured in the format information, whether the time unit is an aggregation time unit.