This application provides data transmission methods and apparatuses, to introduce a buffer status report (BSR) mechanism through multi-link (ML) cooperation, to improve performance of scheduling a station by an ML device. In an example method, a multi-link transmit end determines BSR signaling sent to a multi-link receive end, where the BSR signaling can enable the multi-link receive end to schedule a station of the multi-link transmit end over one or more links. Further, the multi-link transmit end sends the B SR signaling to the multi-link transmit end over the one or more links. This introduces a BSR mechanism through ML cooperation.