Disclosed are a method and device for sending answer information, wherein, when a frequency division duplex (FDD) and a time division duplex (TDD) aggregate, where a TDD cell serves as a primary serving cell and a FDD cell works as a secondary serving cell, a user equipment (UE) groups downlink subframes of the FDD secondary serving cell, and different downlink subframe groups use different hybrid automatic repeat request (HARQ) timing relationships, determines uplink subframes where HARQ-ACK acknowledgment messages corresponding to physical downlink shared channels (PDSCHs) of the downlink subframe groups are transmitted, and sends the HARQ-ACK messages on the determined uplink subframes.