Embodiments of the present invention disclose a data processing method and apparatus, and belong to the field of communications technologies. The method includes: generating a physical layer protocol data unit PPDU, where the PPDU includes a preamble field, a data field, and a middle preamble field, and the preamble in the PPDU includes information used to indicate an insertion frequency of the middle preamble in the data field in the PPDU; and sending the PPDU. The insertion frequency of the middle preamble in the data field is indicated by using a specified field in the preamble. In this way, in different scenarios, the middle preamble may be inserted into the data field at different frequency, thereby reducing overheads of an inserted pilot and improving data transmission performance.