The technology of this application relates to methods and apparatuses for sending and receiving a physical layer protocol data unit. The method includes generating a physical layer protocol data unit (PPDU), where the PPDU includes a short training field, a length of a frequency domain sequence of the short training field is greater than a first length, and the first length is a length, for example, 2048, of a frequency domain sequence of a short training field that is transmitted over a 160 MHz-bandwidth channel. The method further includes sending the PPDU over a target channel, where a bandwidth of the target channel is greater than 160 MHz. According to embodiments of this application, a larger actual channel bandwidth can be achieved, and backward compatibility is implemented.