This application provides a data processing method and a communication apparatus, and relates to the field of communication technologies. The method can be used for downlink data processing and uplink data processing. The communication apparatus may receive a reference signal, and obtain a first matrix based on the reference signal. The first matrix is an autocorrelation matrix whose dimension is N rows and N columns, and N indicates a quantity of channels of an antenna array. Based on the first matrix, channels in different rows of the antenna array are averaged to obtain a second matrix, where a dimension of the second matrix is N/(x×R) rows and N/(x×R) columns; R represents a quantity of channel rows of the antenna array; x represents polarization of the antenna array.