Embodiments of the present invention provide a method for reporting channel state information, user equipment, and a base station, which can improve communication performance of a micro cell network environment and an AAS base station system. The method includes: receiving a reference signal sent by a base station; selecting, based on the reference signal, a precoding matrix from a codebook, where a precoding matrix W included in the codebook is a product of three matrices being W 1 , Z, and W 2 , that is, W = W 1 ZW 2 , where both W 1 and Z are block diagonal matrices, W 1 = a formula (I), Z = a formula (II), each of W 1 and Z includes at least one block matrix, that is, N B ‰¥ 1, and each column of each block matrix Z i in the matrix Z has the following structure formula (III), where [ ] T represents matrix transposition; e i,k represents an n i x1 selection vector, where in the vector, the k th element is 1 and all other elements are 0, and n i is a half of a column quantity of a block matrix X i ; ¸ i,k is a phase shift, ± i,k ‰¥ 0, and ² i,k ‰¥ 0; and sending a precoding matrix indicator PMI to the base station, where the PMI corresponds to the selected precoding matrix, and is used by the base station to obtain the selected precoding matrix W according to the PMI. The embodiments of the present invention are applicable to the field of communications technologies.