A precoding matrix indicator feedback method, comprising: selecting, by a receive end, based on a reference signal, a precoding matrix W from a codebook, wherein a coefficient α is used to perform phase adjustment on φ n in the W, the φ n represents a phase difference between weighted values of a first antenna group and a second antenna group of a transmit end for a transmission signal from a same transmission layer, the φ n ∈ e j 2 ⁢ πn Q, the n is a non-negative integer, the Q is a positive integer, 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; wherein the method further comprises: determining, by the receive end, a rank indicator based on the reference signal, wherein the rank indicator corresponds to the number of useful transmission layers; and the selecting, by a receive end, based on a reference signal, a precoding matrix W from a codebook comprises: selecting, by the receive end, based on the reference signal, the W corresponding to the rank indicator from the codebook; wherein when the rank indicator is 1, the precoding matrix is selected from the codebook defined by: W = W 1 ⋅ W 2 = X L 0 0 X L ⋅ e m 1 αφ n e m 2; wherein the X L = 1 e j 2 ⁢ π L M 1 e j 2 ⁢ π L + 1 M ⋯ 1 e j 2 ⁢ π L + P − 1 M; the L, the P, the m1, the m2 and 1 the M are all positive integers; the L is less than the M; the e m 1 represents a P ×1-dimensional column vector, wherein in the e m 1 an m1 th element is 1 and other elements are all 0; and the e m 1 and the e m 2 are same; wherein the coefficient α =e j 2 π · f, wherein the f ( m 1) represents a function of the m 1. selecting, by a receive end, based on a reference signal, a precoding matrix W from a codebook, wherein a coefficient α is used to perform phase adjustment on φ n in the W, the φ n represents a phase difference between weighted values of a first antenna group and a second antenna group of a transmit end for a transmission signal from a same transmission layer, the φ n ∈ e j 2 ⁢ πn Q, the n is a non-negative integer, the Q is a positive integer, 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; wherein the method further comprises: determining, by the receive end, a rank indicator based on the reference signal, wherein the rank indicator corresponds to the number of useful transmission layers; and the selecting, by a receive end, based on a reference signal, a precoding matrix W from a codebook comprises: selecting, by the receive end, based on the reference signal, the W corresponding to the rank indicator from the codebook; wherein when the rank indicator is 1, the precoding matrix is selected from the codebook defined by: W = W 1 ⋅ W 2 = X L 0 0 X L ⋅ e m 1 αφ n e m 2; wherein the X L = 1 e j 2 ⁢ π L M 1 e j 2 ⁢ π L + 1 M ⋯ 1 e j 2 ⁢ π L + P − 1 M; the L, the P, the m1, the m2 and 1 the M are all positive integers; the L is less than the M; the e m 1 represents a P ×1-dimensional column vector, wherein in the e m 1 an m1 th element is 1 and other elements are all 0; and the e m 1 and the e m 2 are same; wherein the coefficient α =e j 2 π · f, wherein the f ( m 1) represents a function of the m 1. determining, by the receive end, a rank indicator based on the reference signal, wherein the rank indicator corresponds to the number of useful transmission layers; and the selecting, by a receive end, based on a reference signal, a precoding matrix W from a codebook comprises: selecting, by the receive end, based on the reference signal, the W corresponding to the rank indicator from the codebook; wherein when the rank indicator is 1, the precoding matrix is selected from the codebook defined by: W = W 1 ⋅ W 2 = X L 0 0 X L ⋅ e m 1 αφ n e m 2; wherein the X L = 1 e j 2 ⁢ π L M 1 e j 2 ⁢ π L + 1 M ⋯ 1 e j 2 ⁢ π L + P − 1 M; the L, the P, the m1, the m2 and 1 the M are all positive integers; the L is less than the M; the e m 1 represents a P ×1-dimensional column vector, wherein in the e m 1 an m1 th element is 1 and other elements are all 0; and the e m 1 and the e m 2 are same; wherein the coefficient α =e j 2 π · f, wherein the f ( m 1) represents a function of the m 1. selecting, by the receive end, based on the reference signal, the W corresponding to the rank indicator from the codebook; wherein when the rank indicator is 1, the precoding matrix is selected from the codebook defined by: W = W 1 ⋅ W 2 = X L 0 0 X L ⋅ e m 1 αφ n e m 2; wherein the X L = 1 e j 2 ⁢ π L M 1 e j 2 ⁢ π L + 1 M ⋯ 1 e j 2 ⁢ π L + P − 1 M; the L, the P, the m1, the m2 and 1 the M are all positive integers; the L is less than the M; the e m 1 represents a P ×1-dimensional column vector, wherein in the e m 1 an m1 th element is 1 and other elements are all 0; and the e m 1 and the e m 2 are same; wherein the coefficient α =e j 2 π · f, wherein the f ( m 1) represents a function of the m 1.