Disclosed is a method and an apparatus for transmitting acknowledgement information. The apparatus includes: a transmission module, configured to transmit, in a secondary serving cell, a PDSCH to a UE; a determining module, configured to determine an HARQ time sequence relationship corresponding to the secondary serving cell, where the HARQ time sequence relationship is an HARQ time sequence relationship between the PDSCH and an HARQ; and a receiving module, configured to receive, in a primary serving cell according to the HARQ time sequence relationship determined by the determining module, the HARQ-ACK corresponding to the PDSCH. The primary serving cell is a TDD primary serving cell configured by a base station for the UE, the secondary serving cell is a secondary serving cell in N TDD secondary serving cells configured by the base station for the UE, and N is a natural number that is greater than or equal to 1.