A training packet sending method and apparatus, where the method includes generating, by a first device, a training packet, where the training packet includes a preamble, a header, and a training field, and the header includes at least a legacy header, and repeatedly sending, by the first device, the preamble using N channels, sending the legacy header in the header using the N channels, and sending the training field to at least one second device using H channels of the N channels, where N is greater than 1, and H is greater than 1 and less than or equal to N.