A method for establishing a Radio Resource Control, RRC, connection, the method being applied in a communication system comprising a remote terminal device, a relay terminal device and a network device, the remote terminal device communicating with the relay terminal device based on a first communication protocol and the relay terminal device communicating with the network device based on a second communication protocol, characterized in that the method comprises: receiving, by the relay terminal device according to the first communication protocol, a first access-stratum data packet sent from the remote terminal device, the first access-stratum data packet being generated through encapsulating, by the remote terminal device, an RRC connection establishment request message to be sent to the network device, wherein the first access-stratum data packet contains a device identifier of the remote terminal device; generating, by the relay terminal device according to the first access-stratum data packet, a second access-stratum data packet, wherein the second access-stratum data packet contains the device identifier of the remote terminal device; sending, by the relay terminal device according to the second communication protocol, the second access-stratum data packet to the network device; receiving, by the relay terminal device according to the second communication protocol, a third access-stratum data packet sent from the network device, the third access-stratum data packet being generated through encapsulating, by the network device, an RRC connection establishment message to be sent to the remote terminal device, wherein the RRC connection establishment message is generated by the network device according to the device identifier of the remote terminal device and the RRC connection establishment request message, and the third access-stratum data packet contains the device identifier of the remote terminal device; generating, by the relay terminal device, a fourth access-stratum data packet according to the third access-stratum data packet, wherein the fourth access-stratum data packet contains the device identifier of the remote terminal device; and sending, by the relay terminal device according to the first communication protocol, the fourth access-stratum data packet to the remote terminal device. receiving, by the relay terminal device according to the first communication protocol, a first access-stratum data packet sent from the remote terminal device, the first access-stratum data packet being generated through encapsulating, by the remote terminal device, an RRC connection establishment request message to be sent to the network device, wherein the first access-stratum data packet contains a device identifier of the remote terminal device; generating, by the relay terminal device according to the first access-stratum data packet, a second access-stratum data packet, wherein the second access-stratum data packet contains the device identifier of the remote terminal device; sending, by the relay terminal device according to the second communication protocol, the second access-stratum data packet to the network device; receiving, by the relay terminal device according to the second communication protocol, a third access-stratum data packet sent from the network device, the third access-stratum data packet being generated through encapsulating, by the network device, an RRC connection establishment message to be sent to the remote terminal device, wherein the RRC connection establishment message is generated by the network device according to the device identifier of the remote terminal device and the RRC connection establishment request message, and the third access-stratum data packet contains the device identifier of the remote terminal device; generating, by the relay terminal device, a fourth access-stratum data packet according to the third access-stratum data packet, wherein the fourth access-stratum data packet contains the device identifier of the remote terminal device; and sending, by the relay terminal device according to the first communication protocol, the fourth access-stratum data packet to the remote terminal device.