This application provides a data transmission method and apparatus. The method includes coding, by a terminal device, a first transport block to obtain a first coded transport block, where the first transport block includes first data; coding, by the terminal device, indication information to obtain coded indication information, where the indication information is used to indicate whether the terminal device sends a first buffer status report BSR when the terminal device sends the first data, and the first BSR indicates a data amount of to-be-transmitted data currently buffered in a buffer of the terminal device; and sending, by the terminal device, the first coded transport block and the coded indication information to a network device. According to the data transmission method and apparatus provided in embodiments of this application, the network device can directly learn whether the terminal device sends a BSR, so as to reduce a communication delay.