A data transmission method includes generating a signaling field of a PPDU, where a channel bandwidth for transmitting the PPDU includes at least two frequency segments, which include a first frequency segment, and the channel bandwidth includes an RU for MU-MIMO transmission; the signaling field includes a common field and a user-specific field, the user-specific field includes a user field corresponding to the RU, and the user field is a user field of a station to which the RU is allocated and that parks on the first frequency segment; and the common field includes a resource unit allocation subfield corresponding to the RU, indicating the RU and a quantity of user fields corresponding to the RU; and sending the signaling field on the first frequency segment. Some embodiments are applied to a WLAN system that supports 802.11be standard.