A method for feeding back a precoding matrix indicator, comprising: selecting, by a receive end, a precoding matrix W from a codebook based on a reference signal, wherein the W ∈ X 1 θ 1 X 2 θ 2, φ n, a matrix X 1 is determined according to θ 1 a matrix X 2 is determined according to θ 2 and φ n, the θ 1 indicates a phase difference of weighted values for signal transmission between two neighboring antennas in a first antenna group of a transmit end, wherein the signal transmission between the two neighboring antennas in the first antenna group is for a same transmission layer, the θ 2 indicates a phase difference of weighted values for signal transmission between two neighboring antennas in a second antenna group of the transmit end, wherein the signal transmission between the two neighboring antennas in the second antenna group is for a same transmission layer, the φ n indicates a phase difference of weighted values for signal transmission between the first antenna group and the second antenna group, wherein the signal transmission between the first antenna group and the second antenna group is for a same transmission layer, the φ n = e j 2 πn M, the M is a positive integer, the n is a non-negative integer less than the M, θ 1 and θ 2 of at least one precoding matrix in the codebook are different, and the first antenna group and the second antenna group belong to a same multi-antenna system; and sending, by the receive end, a precoding matrix indicator, PMI, to the transmit end, so that the transmit end determines the W according to the PMI, characterised in that the θ 1 = 2 π N A ⋅ i 1 + ⌊ i 4 P ⋅ M ⌋, and the θ 2 = 2 π N A ⋅ i 1 + ⌊ i 4 mod M ⋅ P M ⌋, wherein N=2 k, k is a non-negative integer, A is a positive integer that can be divided exactly by the N, P is a positive integer less than the N, i 1 is a non-negative integer less than (N/A-1), i 4 is a positive integer less than (PM-1), └·┘ is a round-down operation symbol, mod is a modulo operation symbol. selecting, by a receive end, a precoding matrix W from a codebook based on a reference signal, wherein the W ∈ X 1 θ 1 X 2 θ 2, φ n, a matrix X 1 is determined according to θ 1 a matrix X 2 is determined according to θ 2 and φ n, the θ 1 indicates a phase difference of weighted values for signal transmission between two neighboring antennas in a first antenna group of a transmit end, wherein the signal transmission between the two neighboring antennas in the first antenna group is for a same transmission layer, the θ 2 indicates a phase difference of weighted values for signal transmission between two neighboring antennas in a second antenna group of the transmit end, wherein the signal transmission between the two neighboring antennas in the second antenna group is for a same transmission layer, the φ n indicates a phase difference of weighted values for signal transmission between the first antenna group and the second antenna group, wherein the signal transmission between the first antenna group and the second antenna group is for a same transmission layer, the φ n = e j 2 πn M, the M is a positive integer, the n is a non-negative integer less than the M, θ 1 and θ 2 of at least one precoding matrix in the codebook are different, and the first antenna group and the second antenna group belong to a same multi-antenna system; and sending, by the receive end, a precoding matrix indicator, PMI, to the transmit end, so that the transmit end determines the W according to the PMI, characterised in that the θ 1 = 2 π N A ⋅ i 1 + ⌊ i 4 P ⋅ M ⌋, and the θ 2 = 2 π N A ⋅ i 1 + ⌊ i 4 mod M ⋅ P M ⌋, wherein N=2 k, k is a non-negative integer, A is a positive integer that can be divided exactly by the N, P is a positive integer less than the N, i 1 is a non-negative integer less than (N/A-1), i 4 is a positive integer less than (PM-1), └·┘ is a round-down operation symbol, mod is a modulo operation symbol.