A method for backing up a TCP connection includes a data transmission process and a data receiving process. The data transmission process includes obtaining, by an AMB of a transmitting end, boundary information of data; and backing up the data and the boundary information of the data to a SMB of the transmitting end. The data receiving process includes backing up, by the SMB, data received from a peer side of the TCP connection and the boundary information of the data received by the peer side to the AMB; and deleting the data received by the peer side from the data backed up by the SMB during the transmission process according to the boundary information of the data received by the peer side. The disclosure also provides an apparatus for backing up a TCP connection.