A pre-coding method for use in a cooperative relay system, the method comprising: obtaining, by a transmitter, pre-coding matrixes (P 1,P 2) of local optimal sub-channels which are from a transmitter to respective relay stations, wherein single links are established between the transmitter and the respective relay stations, each single link includes a plurality of sub-channels, and the local optimal sub-channel, to which data is mapped for transmission, is one or more sub-channels of multi-antenna channels; performing, by the transmitter, a Singular Value Decomposition, SVD, operation on a matrix comprising the pre-coding matrixes (P 1,P 2) of the local optimal sub-channels according to the following formula: P 1 P 2 = U ⁢ Σ V H where, both U and V are 4×4 unitary matrixes, ∑ is a diagonal matrix, and H is a conjugate transpose operation of the matrix V; obtaining, by the transmitter, a pre-coding matrix P of a synthesized optimal sub-channel according to a result of the SVD operation on the pre-coding matrixes (P 1,P 2) of the local optimal sub-channels, wherein the synthesized optimal sub-channel is formed by the local optimal sub-channels of the single links, wherein P = U 1: 2 where, U 1:2 is a sub-matrix that is constructed by first two columns of the matrix U; and transmitting, by the transmitter, data that is coded through the pre-coding matrix P of the synthesized optimal sub-channel to the respective relay stations, wherein the obtaining the pre-coding matrixes of the local optimal sub-channels which are from the transmitter to the respective relay stations comprises: receiving, by the transmitter, channel information (H 1,H 2) of the single links from the respective relay stations; performing, by the transmitter, a SVD operation on the channel information (H 1,H 2) of the single links according to the following formula: { H 1 = U 1 Σ 1 V 1 H H 2 = U 2 Σ 2 V 2 H where, U 1, V 1 and U 2, V 2 are all 4x4 unitary matrixes, ∑ 1 and ∑ 2 are diagonal matrixes, H is a conjugate transpose operation of a matrix X, and X is V 1 or V 2; and obtaining, by the transmitter, the pre-coding matrixes (P 1,P 2) of the local optimal sub-channels according to a result of the SVD operation on the channel information (H 1,H 2) of the single links, wherein { P 1 = V 1 1: 2 P 2 = V 2 1: 2 where, 1:2 are respectively sub-matrixes which are constructed by first two columns of the matrix X. obtaining, by a transmitter, pre-coding matrixes (P 1,P 2) of local optimal sub-channels which are from a transmitter to respective relay stations, wherein single links are established between the transmitter and the respective relay stations, each single link includes a plurality of sub-channels, and the local optimal sub-channel, to which data is mapped for transmission, is one or more sub-channels of multi-antenna channels; performing, by the transmitter, a Singular Value Decomposition, SVD, operation on a matrix comprising the pre-coding matrixes (P 1,P 2) of the local optimal sub-channels according to the following formula: P 1 P 2 = U ⁢ Σ V H where, both U and V are 4×4 unitary matrixes, ∑ is a diagonal matrix, and H is a conjugate transpose operation of the matrix V; obtaining, by the transmitter, a pre-coding matrix P of a synthesized optimal sub-channel according to a result of the SVD operation on the pre-coding matrixes (P 1,P 2) of the local optimal sub-channels, wherein the synthesized optimal sub-channel is formed by the local optimal sub-channels of the single links, wherein P = U 1: 2 where, U 1:2 is a sub-matrix that is constructed by first two columns of the matrix U; and transmitting, by the transmitter, data that is coded through the pre-coding matrix P of the synthesized optimal sub-channel to the respective relay stations, wherein the obtaining the pre-coding matrixes of the local optimal sub-channels which are from the transmitter to the respective relay stations comprises: receiving, by the transmitter, channel information (H 1,H 2) of the single links from the respective relay stations; performing, by the transmitter, a SVD operation on the channel information (H 1,H 2) of the single links according to the following formula: { H 1 = U 1 Σ 1 V 1 H H 2 = U 2 Σ 2 V 2 H where, U 1, V 1 and U 2, V 2 are all 4x4 unitary matrixes, ∑ 1 and ∑ 2 are diagonal matrixes, H is a conjugate transpose operation of a matrix X, and X is V 1 or V 2; and obtaining, by the transmitter, the pre-coding matrixes (P 1,P 2) of the local optimal sub-channels according to a result of the SVD operation on the channel information (H 1,H 2) of the single links, wherein { P 1 = V 1 1: 2 P 2 = V 2 1: 2 where, 1:2 are respectively sub-matrixes which are constructed by first two columns of the matrix X.