Provided are CSI feedback and receiving methods, apparatuses, a device, and a storage medium. The method includes: a terminal determines PMI, the PMI includes at least one of: first base vector information, second base vector information, second coefficient amplitude information or phase information; for one transmission layer, a frequency domain resource in one preset frequency domain unit corresponds to one precoding vector, the precoding vector is a linear combination of first base vectors, and weighting coefficients used in the linear combination of the first base vectors are first coefficients; on multiple frequency domain units contained in a CSI feedback band, a vector composed of first coefficients corresponding to a same first base vector is a linear combination of second base vectors, and weighting coefficients used in the linear combination of the second base vectors are second coefficients; and the terminal feeds back CSI containing the PMI to a base station.