A precoding matrix determining method, comprising: sending, by a base station, a plurality of groups of first reference signals, wherein the plurality of groups of first reference signals are in a one-to-one correspondence with a plurality of dimensions of an antenna array, and each of the plurality of groups of first reference signals is used by a terminal to estimate spatial correlation matrix information in a corresponding dimension; receiving the spatial correlation matrix information fed back by the terminal based on the plurality of groups of first reference signals; and determining a stage-1 precoding matrix based on the spatial correlation matrix information; wherein after the determining a stage-1 precoding matrix based on the spatial correlation matrix information, the method further comprises: sending at least one second reference signal encoded by the stage-1 precoding matrix, wherein the at least one second reference signal is in a one-to-one correspondence with at least one spatial direction; receiving a stage-2 precoding matrix indicator PMI fed back by the terminal based on the at least one second reference signal; and determining a stage-2 precoding matrix based on the stage-2 PMI; wherein a codebook used to feed back the stage-2 PMI is: W = W 1 W 2 = G 1 G 2 β 1 β 2 ⋮ β M αω j θ η 1 η 2 ⋮ η M, wherein W 1 is determined based on the stage-1 precoding matrix, G 1 is used to represent a group of bases in a first polarization direction, G 2 is used to represent a group of bases in a second polarization direction, G 1 = [g 1 g 2 ··· g M], G 2 = g 1 ′ g 2 ′ ⋯ g M ′, a quantity of non-zero elements in W 2 is greater than 1, β and η are quantized coefficients, α is an amplitude difference between the polarization directions, and θ is a phase difference between the polarization directions. sending, by a base station, a plurality of groups of first reference signals, wherein the plurality of groups of first reference signals are in a one-to-one correspondence with a plurality of dimensions of an antenna array, and each of the plurality of groups of first reference signals is used by a terminal to estimate spatial correlation matrix information in a corresponding dimension; receiving the spatial correlation matrix information fed back by the terminal based on the plurality of groups of first reference signals; and determining a stage-1 precoding matrix based on the spatial correlation matrix information; wherein after the determining a stage-1 precoding matrix based on the spatial correlation matrix information, the method further comprises: sending at least one second reference signal encoded by the stage-1 precoding matrix, wherein the at least one second reference signal is in a one-to-one correspondence with at least one spatial direction; receiving a stage-2 precoding matrix indicator PMI fed back by the terminal based on the at least one second reference signal; and determining a stage-2 precoding matrix based on the stage-2 PMI; wherein a codebook used to feed back the stage-2 PMI is: W = W 1 W 2 = G 1 G 2 β 1 β 2 ⋮ β M αω j θ η 1 η 2 ⋮ η M, wherein W 1 is determined based on the stage-1 precoding matrix, G 1 is used to represent a group of bases in a first polarization direction, G 2 is used to represent a group of bases in a second polarization direction, G 1 = [g 1 g 2 ··· g M], G 2 = g 1 ′ g 2 ′ ⋯ g M ′, a quantity of non-zero elements in W 2 is greater than 1, β and η are quantized coefficients, α is an amplitude difference between the polarization directions, and θ is a phase difference between the polarization directions. sending at least one second reference signal encoded by the stage-1 precoding matrix, wherein the at least one second reference signal is in a one-to-one correspondence with at least one spatial direction; receiving a stage-2 precoding matrix indicator PMI fed back by the terminal based on the at least one second reference signal; and determining a stage-2 precoding matrix based on the stage-2 PMI; wherein a codebook used to feed back the stage-2 PMI is: W = W 1 W 2 = G 1 G 2 β 1 β 2 ⋮ β M αω j θ η 1 η 2 ⋮ η M, wherein W 1 is determined based on the stage-1 precoding matrix, G 1 is used to represent a group of bases in a first polarization direction, G 2 is used to represent a group of bases in a second polarization direction, G 1 = [g 1 g 2 ··· g M], G 2 = g 1 ′ g 2 ′ ⋯ g M ′, a quantity of non-zero elements in W 2 is greater than 1, β and η are quantized coefficients, α is an amplitude difference between the polarization directions, and θ is a phase difference between the polarization directions.