A Channel State Information, CSI, feedback method, comprising: determining (S301) a first precoding matrix W 1 in a set of first precoding matrices, and determining a first precoding matrix index value corresponding to the first precoding matrix W 1 , the first precoding matrix W 1 consisting of beam groups for a plurality of antenna groups of an antenna array; determining (S302) a second precoding matrix W 2 in a set of second precoding matrices, and determining a second precoding matrix index value corresponding to the second precoding matrix W 2 , the second precoding matrix W 2 comprising a beam selection section for selecting beams from the beam groups for each antenna group and a phase adjustment section for adjusting phases among the plurality of antenna groups; and feeding (S303) back the first precoding matrix index value and the second precoding matrix index value to an access device, determining, by the access device, a corresponding beam group from the beam groups for each antenna group in accordance with the first precoding matrix index value, conducting, by the access device, a corresponding beam selection section and phase adjustment section with respect to the determined beam group in accordance with the second precoding matrix index value, and selecting, by the access device, corresponding precoding matrices from the set of first precoding matrices and the set of second precoding matrix in accordance with the first precoding matrix index value and the second precoding matrix index value, and implementing calculation on the selected precoding matrices to obtain a precoding matrix W for data transmission. determining (S301) a first precoding matrix W 1 in a set of first precoding matrices, and determining a first precoding matrix index value corresponding to the first precoding matrix W 1 , the first precoding matrix W 1 consisting of beam groups for a plurality of antenna groups of an antenna array; determining (S302) a second precoding matrix W 2 in a set of second precoding matrices, and determining a second precoding matrix index value corresponding to the second precoding matrix W 2 , the second precoding matrix W 2 comprising a beam selection section for selecting beams from the beam groups for each antenna group and a phase adjustment section for adjusting phases among the plurality of antenna groups; and feeding (S303) back the first precoding matrix index value and the second precoding matrix index value to an access device, determining, by the access device, a corresponding beam group from the beam groups for each antenna group in accordance with the first precoding matrix index value, conducting, by the access device, a corresponding beam selection section and phase adjustment section with respect to the determined beam group in accordance with the second precoding matrix index value, and selecting, by the access device, corresponding precoding matrices from the set of first precoding matrices and the set of second precoding matrix in accordance with the first precoding matrix index value and the second precoding matrix index value, and implementing calculation on the selected precoding matrices to obtain a precoding matrix W for data transmission. <EOS>