A channel information sending method, a data sending method, and a device are provided, to improve feedback precision of a precoding matrix. A first device includes: a receiving module, configured to receive a reference signal; a processing module, configured to measure the reference signal to obtain first channel information and second channel information; and a sending module, configured to send the first channel information and the second channel information. When generating the precoding matrix, the second device may perform weighted combination on M first vectors based on the weighted combination factor indicated by the received second channel information, instead of selecting only one eigenvector from a plurality of eigenvectors, so that the generated precoding matrix is more precise.