A method for establishing a data bearer in a radio communication system supporting multi-connectivity, wherein the radio communication system comprises a user equipment and at least two base stations connected to the user equipment, the at least two base stations comprise at least one macro base station and at least one small base station, the method comprising: Receiving information related to the data bearer; determining configuration information of respective protocol layers in a user plane protocol stack, that is established at at least one of the macro base station and the small base station for the data bearer, according to the related information and the user plane protocol stack; and sending to the user equipment a radio resource control message including the configuration information to establish the data bearer; wherein the user plane protocol stack established at the at least one of the macro base station and the small base station for the data bearer comprises a packet data convergence protocol layer, a radio link control layer, a media access control layer, and a physical layer; wherein the macro base station is connected to a gateway to transmit data, and the small base station comprises no radio resource control entity, the method further comprising: receiving configuration information of the respective protocol layers determined at the small base station; and forming the radio resource control message at the macro base station, wherein the radio resource control message includes configuration information determined at the small base station or includes both configuration information determined at the small base station and configuration information determined at the macro base station, and the radio resource control message further includes an identifier of the small base station; and the method characterized by the following steps, sending from the macro base station to the user equipment the radio resource control message, the radio resource control message including synchronization information enabling the user equipment and the small base station to use the configuration information in synchronization, the synchronization information comprising an activation time like mechanism; and receiving at the macro base station a response to the radio resource control message from the user equipment and forwarding the response to the small base station. Receiving information related to the data bearer; determining configuration information of respective protocol layers in a user plane protocol stack, that is established at at least one of the macro base station and the small base station for the data bearer, according to the related information and the user plane protocol stack; and sending to the user equipment a radio resource control message including the configuration information to establish the data bearer; wherein the user plane protocol stack established at the at least one of the macro base station and the small base station for the data bearer comprises a packet data convergence protocol layer, a radio link control layer, a media access control layer, and a physical layer; wherein the macro base station is connected to a gateway to transmit data, and the small base station comprises no radio resource control entity, the method further comprising: receiving configuration information of the respective protocol layers determined at the small base station; and forming the radio resource control message at the macro base station, wherein the radio resource control message includes configuration information determined at the small base station or includes both configuration information determined at the small base station and configuration information determined at the macro base station, and the radio resource control message further includes an identifier of the small base station; and the method characterized by the following steps, sending from the macro base station to the user equipment the radio resource control message, the radio resource control message including synchronization information enabling the user equipment and the small base station to use the configuration information in synchronization, the synchronization information comprising an activation time like mechanism; and receiving at the macro base station a response to the radio resource control message from the user equipment and forwarding the response to the small base station. receiving configuration information of the respective protocol layers determined at the small base station; and forming the radio resource control message at the macro base station, wherein the radio resource control message includes configuration information determined at the small base station or includes both configuration information determined at the small base station and configuration information determined at the macro base station, and the radio resource control message further includes an identifier of the small base station; and the method characterized by the following steps, sending from the macro base station to the user equipment the radio resource control message, the radio resource control message including synchronization information enabling the user equipment and the small base station to use the configuration information in synchronization, the synchronization information comprising an activation time like mechanism; and receiving at the macro base station a response to the radio resource control message from the user equipment and forwarding the response to the small base station.