An interface establishing method, wherein the method comprises: sending (S201, S302, S602), by a serving node, first instruction information to an anchor node, wherein the first instruction information is used to instruct to establish a first interface between the serving node and the anchor node; receiving (S202, S303, S603), by the serving node, response information from the anchor node in response to the first instruction information; wherein the first interface comprises at least a control plane interface between the serving node and the anchor node, the control plane interface is used to: transmit a radio resource control, RRC, message of a user terminal, and establish an air interface connection between the serving node and the user terminal; wherein the method further comprises: receiving (S304, S604), by the serving node, an uplink RRC message from the user terminal, wherein the uplink RRC message is a RRC message carried in a signaling radio bearer 0, SRBO, processing (S304, S605), by the serving node, the uplink RRC message in the SRBO, generating (S306, S608), by the serving node, a downlink RRC message carried in the SRBO, and sending (S30, S611) the downlink RRC message to the user terminal through the air interface connection, and wherein the method further comprises: receiving (S304, S604), by the serving node, an uplink RRC message from the user terminal, wherein the uplink RRC message is a RRC message carried in a signaling radio bearer 1, SRB1, or a signaling radio bearer 2, SRB2; sending (S305, S606), by the serving node, through the first interface, the RRC message carried in the SRB1 or the SRB2 in the uplink RRC message to the anchor node for processing; and receiving (S307, S610), by the serving node through the first interface, a downlink RRC message carried in the SRB 1 or the SRB2 from the anchor node, and sending (S307, S611), by the serving node, the downlink RRC message carried in the SRB1 or the SRB2 to the user terminal through the air interface connection. sending (S201, S302, S602), by a serving node, first instruction information to an anchor node, wherein the first instruction information is used to instruct to establish a first interface between the serving node and the anchor node; receiving (S202, S303, S603), by the serving node, response information from the anchor node in response to the first instruction information; wherein the first interface comprises at least a control plane interface between the serving node and the anchor node, the control plane interface is used to: transmit a radio resource control, RRC, message of a user terminal, and establish an air interface connection between the serving node and the user terminal; receiving (S304, S604), by the serving node, an uplink RRC message from the user terminal, wherein the uplink RRC message is a RRC message carried in a signaling radio bearer 0, SRBO, processing (S304, S605), by the serving node, the uplink RRC message in the SRBO, generating (S306, S608), by the serving node, a downlink RRC message carried in the SRBO, and sending (S30, S611) the downlink RRC message to the user terminal through the air interface connection, and receiving (S304, S604), by the serving node, an uplink RRC message from the user terminal, wherein the uplink RRC message is a RRC message carried in a signaling radio bearer 1, SRB1, or a signaling radio bearer 2, SRB2; sending (S305, S606), by the serving node, through the first interface, the RRC message carried in the SRB1 or the SRB2 in the uplink RRC message to the anchor node for processing; and receiving (S307, S610), by the serving node through the first interface, a downlink RRC message carried in the SRB 1 or the SRB2 from the anchor node, and sending (S307, S611), by the serving node, the downlink RRC message carried in the SRB1 or the SRB2 to the user terminal through the air interface connection. <EOS>