A data transmission method, and new AS sublayer entity. The data transmission method is applicable in a new AS sublayer entity, and comprises: receiving a quality of service flow (QoS flow) having a first flow ID; mapping the QoS flow to one or more data radio bearers (DRB) to obtain a protocol data unit (PDU) packet, wherein the PDU packet carries a second flow ID corresponding to the QoS flow, and the first flow ID and the second flow ID have a one-to-one correspondence relationship with respect to combinations of the data radio bearer (DRB) IDs; and transmitting the PDU packet.