Embodiments of this application disclose a precoding matrix determining method and apparatus, to determine a stage-1 precoding matrix based on indication information that is of a spatial correlation matrix and that is fed back by a terminal, thereby implementing three-dimensional precoding based on a channel state and increasing a channel capacity. The method includes: sending, by a base station, a plurality of groups of first reference signals, where 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.