A retransmission method at a user equipment, comprising: after transmitting two channel-coded codewords in initial transmission, receiving a retransmission indication, where the retransmission indication comprises an identifier of one channel-coded codeword to be retransmitted; further comprising: acquiring precoding matrix determining information of the retransmission given by an index number of the precoding matrix for the retransmission indicated by a redundant bit or an added bit in UL grant signaling of the initial transmission; according to the precoding matrix determining information, determining a precoding matrix of each symbol of the one channel-coded codeword to be retransmitted, where the precoding matrix is a precoding matrix for the retransmission, the precoding matrix for the retransmission is determined according to a mapping relationship, and the mapping relationship is established between the precoding matrix for the retransmission and a precoding matrix for the initial transmission; and after coding, by using the precoding matrix for the retransmission, the each symbol of the one channel-coded codeword to be retransmitted, sending the coded symbol through an antenna; wherein a rank of the precoding matrix for the retransmission and a rank of the precoding matrix for the initial transmission are different; wherein after the transmitting the two channel-coded codewords in the initial transmission and before the transmitting one channel-coded codeword in the retransmission there is no uplink grant, UL grant, signaling. after transmitting two channel-coded codewords in initial transmission, receiving a retransmission indication, where the retransmission indication comprises an identifier of one channel-coded codeword to be retransmitted; further comprising: acquiring precoding matrix determining information of the retransmission given by an index number of the precoding matrix for the retransmission indicated by a redundant bit or an added bit in UL grant signaling of the initial transmission; according to the precoding matrix determining information, determining a precoding matrix of each symbol of the one channel-coded codeword to be retransmitted, where the precoding matrix is a precoding matrix for the retransmission, the precoding matrix for the retransmission is determined according to a mapping relationship, and the mapping relationship is established between the precoding matrix for the retransmission and a precoding matrix for the initial transmission; and after coding, by using the precoding matrix for the retransmission, the each symbol of the one channel-coded codeword to be retransmitted, sending the coded symbol through an antenna; wherein a rank of the precoding matrix for the retransmission and a rank of the precoding matrix for the initial transmission are different; wherein after the transmitting the two channel-coded codewords in the initial transmission and before the transmitting one channel-coded codeword in the retransmission there is no uplink grant, UL grant, signaling. acquiring precoding matrix determining information of the retransmission given by an index number of the precoding matrix for the retransmission indicated by a redundant bit or an added bit in UL grant signaling of the initial transmission; according to the precoding matrix determining information, determining a precoding matrix of each symbol of the one channel-coded codeword to be retransmitted, where the precoding matrix is a precoding matrix for the retransmission, the precoding matrix for the retransmission is determined according to a mapping relationship, and the mapping relationship is established between the precoding matrix for the retransmission and a precoding matrix for the initial transmission; and after coding, by using the precoding matrix for the retransmission, the each symbol of the one channel-coded codeword to be retransmitted, sending the coded symbol through an antenna; wherein a rank of the precoding matrix for the retransmission and a rank of the precoding matrix for the initial transmission are different; wherein after the transmitting the two channel-coded codewords in the initial transmission and before the transmitting one channel-coded codeword in the retransmission there is no uplink grant, UL grant, signaling.