This application provides a HARQ codebook generation method and a related device. The method includes: receiving, by a terminal, first information, where the first information is used to indicate carriers configured by the access network device for the terminal, the configured carriers include a first carrier and a second carrier,HARQ feedback information of the first carrier and HARQ feedback information of the second carrier are transmitted on an uplink control channel of the first carrier, and a transmission time unit length of the first carrier is not equal to a transmission time unit length of the second carrier; and generating, by the terminal based on HARQ timing of the configured carriers and a relationship between the transmission time unit length of the first carrier and the transmission time unit length of the second carrier, a HARQ codebook transmitted on the uplink control channel of the first carrier.