This application provides a communication method, to provide a codebook of a higher-order precoding matrix, and help increase a quantity of layers of data, thereby helping improve a data transmission capability and improving a throughput. The method includes: receiving, by a first device, a reference signal used for channel measurement; and sending, by the first device, at least one precoding matrix indicator PMI and a rank indication RI based on the reference signal, where the PMI is used to indicate a precoding matrix in a codebook corresponding to the RI, the precoding matrix in the codebook includes a plurality of matrices in a one-to-one correspondence with a plurality of antenna port groups, a matrix corresponding to one antenna port group or each of at least two antenna port groups has two different inter-antenna-port-group phase factors, and any two column vectors in the precoding matrix are orthogonal to each other.