A hybrid automatic repeat request-acknowledgment, HARQ-ACK, feedback method in a 3GPP system, wherein the method comprises: sending, by a network device to a terminal device, second indication information by radio resource control, RRC, signaling, wherein the second indication information comprises a preset feedback delay, wherein the preset feedback delay is a minimum difference between a transmitting time interval, TTI, for transmitting downlink data and a target TTI for feeding back the HARQ-ACK feedback corresponding to the downlink data; sending, by the network device to the terminal device, at least one piece of downlink data and downlink control information, DCI, corresponding to the downlink data, wherein the DCI comprises first indication information, the first indication information indicates the target TTI for transmitting the HARQ-ACK feedback information, wherein the HARQ-ACK feedback information corresponds to the at least one piece of downlink data, and the HARQ-ACK feedback information indicates a reception status of the at least one piece of downlink data; receiving, by the network device, the HARQ-ACK feedback information from the terminal device in the target TTI, wherein the first indication information comprises a feedback delay of downlink data and the HARQ-ACK feedback information is generated at the terminal device by detecting whether a feedback delay of the last piece of downlink data received before the target TTI is greater than the preset feedback delay such that if a detection result is that the feedback delay is greater than the preset feedback delay, determining, by the terminal device, that there is downlink data that has not been received; and if a detection result is that the feedback delay is not greater than the preset feedback delay, determining that there is no downlink data that has not been received; and decoding, by the network device, the HARQ-ACK feedback information based on the second indication information. sending, by a network device to a terminal device, second indication information by radio resource control, RRC, signaling, wherein the second indication information comprises a preset feedback delay, wherein the preset feedback delay is a minimum difference between a transmitting time interval, TTI, for transmitting downlink data and a target TTI for feeding back the HARQ-ACK feedback corresponding to the downlink data; sending, by the network device to the terminal device, at least one piece of downlink data and downlink control information, DCI, corresponding to the downlink data, wherein the DCI comprises first indication information, the first indication information indicates the target TTI for transmitting the HARQ-ACK feedback information, wherein the HARQ-ACK feedback information corresponds to the at least one piece of downlink data, and the HARQ-ACK feedback information indicates a reception status of the at least one piece of downlink data; receiving, by the network device, the HARQ-ACK feedback information from the terminal device in the target TTI, wherein the first indication information comprises a feedback delay of downlink data and the HARQ-ACK feedback information is generated at the terminal device by detecting whether a feedback delay of the last piece of downlink data received before the target TTI is greater than the preset feedback delay such that if a detection result is that the feedback delay is greater than the preset feedback delay, determining, by the terminal device, that there is downlink data that has not been received; and if a detection result is that the feedback delay is not greater than the preset feedback delay, determining that there is no downlink data that has not been received; and decoding, by the network device, the HARQ-ACK feedback information based on the second indication information.