An uplink data transmission method, comprising: determining, by a terminal device, process status information, wherein the process status information comprises a use status of at least one Hybrid Automatic Repeat Request, HARQ, process, and the use status of the HARQ process is any one of the following: the HARQ process is not used to send uplink data, the HARQ process is used to send uplink data and no feedback information has been received, or the HARQ process is used to send uplink data and feedback information has been received; and sending, by the terminal device, the process status information to an access network device; wherein the process status information comprises a use status of a HARQ process corresponding to uplink data sent in a first time unit; and when the use status of the HARQ process corresponding to the uplink data sent in the first time unit is that the HARQ process is used to send the uplink data and no feedback information has been received, the sending, by the terminal device, the process status information to an access network device comprises: sending, by the terminal device, the process status information to the access network device before a second time unit, wherein the second time unit follows the first time unit, and the second time unit is not later than a latest sending time unit in which the access network device sends feedback information corresponding to the uplink data sent in the first time unit. determining, by a terminal device, process status information, wherein the process status information comprises a use status of at least one Hybrid Automatic Repeat Request, HARQ, process, and the use status of the HARQ process is any one of the following: the HARQ process is not used to send uplink data, the HARQ process is used to send uplink data and no feedback information has been received, or the HARQ process is used to send uplink data and feedback information has been received; and sending, by the terminal device, the process status information to an access network device; wherein the process status information comprises a use status of a HARQ process corresponding to uplink data sent in a first time unit; and when the use status of the HARQ process corresponding to the uplink data sent in the first time unit is that the HARQ process is used to send the uplink data and no feedback information has been received, the sending, by the terminal device, the process status information to an access network device comprises: sending, by the terminal device, the process status information to the access network device before a second time unit, wherein the second time unit follows the first time unit, and the second time unit is not later than a latest sending time unit in which the access network device sends feedback information corresponding to the uplink data sent in the first time unit. sending, by the terminal device, the process status information to the access network device before a second time unit, wherein the second time unit follows the first time unit, and the second time unit is not later than a latest sending time unit in which the access network device sends feedback information corresponding to the uplink data sent in the first time unit.