According to embodiments, a method includes: receiving first indication information, where the first indication information indicates a TBS threshold; receiving second indication information from a network device, where the second indication information indicates a quantity N of candidate TBSs; obtaining a first TBS set, where a quantity of elements in the first TBS set is equal to the quantity N of the candidate TBSs, and a largest TBS in the first TBS set is less than or equal to the TBS threshold indicated by the first indication information; selecting, from the first TBS set, a target TBS to be used for transmission of first data, where the target TBS is a smallest TBS, in the first TBS set, greater than or equal to a TBS required by the first data; and sending the first data to the network device based on the target TBS.