Embodiments of this application provide a method and an apparatus for transmitting a physical layer protocol data unit, to design a short training field sequence for a larger channel bandwidth. The short training field sequence designed in this application has a smaller peak-to-average power ratio PAPR and better performance. The method includes: generating a physical layer protocol data unit PPDU that complies with the 802.11be standard, where the PPDU includes a short training field, and a quantity of subcarriers of a frequency domain sequence of the short training field is greater than 2048; and sending the PPDU on a target channel, where a bandwidth of the target channel is greater than or equal to 160 MHz.