This application provides methods and apparatus for sending feedback information. By binding a BAR-BA feedback manner, that is, first a request and then a feedback, when it is determined that data retransmission is performed by using a hybrid automatic repeat request (HARQ) mechanism, duration of an acknowledgment operation performed by a data receive end on retransmitted data may be increased. Alternatively, the receive end estimates duration required for feeding back a receiving status of the retransmitted data, and feeds back the duration to a transmit end. The transmit end may therefore adaptively adjust duration of the retransmitted data based on a feedback capability of the receive end, to ensure that the feedback of the receive end on the receiving status of the retransmitted data is within a short inter-frame space (SIFS).