Embodiments of the present invention provide a data transmission method, an apparatus, and a communications system. The method includes sending, by a macro base station, a configuration request message to an access node, where the configuration request message includes a bearer configuration parameter that carries a radio bearer (RB) identifier; receiving, by the macro base station, a configuration success message from the access node, where the configuration success message carries at least physical layer parameter configuration information that is configured by the access node for a user equipment; and sending, by the macro base station, a reconfiguration message to the user equipment. The reconfiguration message includes at least the RB identifier and/or a logical channel identifier that is reconfigured to transmit on the access node and the physical layer parameter configuration information of the access node.