One example method includes receiving, by a terminal, indication information sent by a base station, where the indication information indicates a precoding matrix in a first precoding matrix set and a transmission rank corresponding to the precoding matrix, and the precoding matrix is used to precode transmit data streams at r transmission layers to obtain signals to be sent on N transmission ports of the terminal; and when r>1, a nonscalar part of a precoding matrix whose transmission rank is r in the first precoding matrix set is obtained by combining columns in nonscalar parts of r precoding matrices, and the r precoding matrices are precoding matrices selected from all precoding matrices whose transmission ranks are 1; and determining, by the terminal based on the indication information, the precoding matrix for precoding the transmit data streams.