An uplink information transmission method, a terminal device, and an access network device are provided. The method includes: obtaining, by a terminal device, indication information for sending uplink information on a first symbol set of a target carrier; and sending, by the terminal device, the uplink information in a second time in a time occupied by the first symbol set. The second time is a time in the time occupied by the first symbol set other than a first time, and is a time in which the terminal device is allowed to access a channel of the target carrier to send the uplink information.