The present disclosure relates to a method for determining a precoding matrix indicator, a user equipment (UE), a base station (e.g., eNB), and a 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 two matrices W1 and W2, where W1 is a block diagonal matrix, where each block matrix is a Kronecker product of a matrix Ai and a matrix Bi; and sending a precoding matrix indicator (PMI) to the base station, where the PMI corresponds to the selected precoding matrix, so that the base station obtains the precoding matrix according to the PMI.