A method and an apparatus for sending hybrid automatic repeat request acknowledgement/negative acknowledgement information are disclosed, and relate to the communications field, to specify a mechanism for feeding back information indicating whether a decoding result of downlink data repeatedly transmitted in a slot is correct. The method includes: determining a first downlink data occasion set based on a time domain resource indicated by a time domain resource allocation (TDRA) table; determining a first downlink data occasion based on a start time domain resource for sending downlink data; adding feedback information (for example, information indicating whether a decoding result of the downlink data is correct) to a feedback location corresponding to the first downlink data occasion; determining a feedback slot based on a slot to which the start time domain resource for sending the downlink data belongs and a first offset K1; and feeding back a HARQ-ACK codebook in the feedback slot.