A precoding matrix set determining method, comprising: determining, by a first network and based on a first parameter indication information sent by a second network device, a parameter used for determining a precoding matrix set, wherein the parameter comprises at least one of a phase parameter, an amplitude parameter, a quantity of vectors in the precoding matrix set, a quantity of vectors in a first codebook set in dual-codebook feedback, and a quantity of vectors in a second codebook set in the dual-codebook feedback, and the parameter is not fixed; wherein the parameter is terminal-specific; and determining the precoding matrix set by using the parameter, wherein the precoding matrix set comprises at least one precoding matrix; wherein the parameter comprises at least one of a first phase value φ 1, an amplitude a m, n of an element (m, n) in the precoding matrix set, the quantity N of vectors in the precoding matrix set, and a quantity M of elements in each vector in the precoding matrix set, and other parameters, except the parameter, in the first phase value φ 1, the amplitude a m, n of the element (m, n) in the precoding matrix set, the quantity N of vectors in the precoding matrix set, and the quantity M of elements in each vector in the precoding matrix set, are preset; and the determining the precoding matrix set by using the parameter comprises: determining, by using a phase range [0, φ 1], the amplitude a m, n, the quantity N, and the quantity M, a vector that forms the precoding matrix set; wherein 0 is a minimum value of a phase difference between two adjacent antennas in a vector in the precoding matrix set; and the first phase value φ 1 is a maximum value of the phase difference between two adjacent antennas in the vector in the precoding matrix set. determining, by a first network and based on a first parameter indication information sent by a second network device, a parameter used for determining a precoding matrix set, wherein the parameter comprises at least one of a phase parameter, an amplitude parameter, a quantity of vectors in the precoding matrix set, a quantity of vectors in a first codebook set in dual-codebook feedback, and a quantity of vectors in a second codebook set in the dual-codebook feedback, and the parameter is not fixed; wherein the parameter is terminal-specific; and determining the precoding matrix set by using the parameter, wherein the precoding matrix set comprises at least one precoding matrix; wherein the parameter comprises at least one of a first phase value φ 1, an amplitude a m, n of an element (m, n) in the precoding matrix set, the quantity N of vectors in the precoding matrix set, and a quantity M of elements in each vector in the precoding matrix set, and other parameters, except the parameter, in the first phase value φ 1, the amplitude a m, n of the element (m, n) in the precoding matrix set, the quantity N of vectors in the precoding matrix set, and the quantity M of elements in each vector in the precoding matrix set, are preset; and the determining the precoding matrix set by using the parameter comprises: determining, by using a phase range [0, φ 1], the amplitude a m, n, the quantity N, and the quantity M, a vector that forms the precoding matrix set; wherein 0 is a minimum value of a phase difference between two adjacent antennas in a vector in the precoding matrix set; and the first phase value φ 1 is a maximum value of the phase difference between two adjacent antennas in the vector in the precoding matrix set. determining, by using a phase range [0, φ 1], the amplitude a m, n, the quantity N, and the quantity M, a vector that forms the precoding matrix set; wherein 0 is a minimum value of a phase difference between two adjacent antennas in a vector in the precoding matrix set; and the first phase value φ 1 is a maximum value of the phase difference between two adjacent antennas in the vector in the precoding matrix set.