A precoding matrix determination method and a precoding matrix determination device are provided. The precoding matrix determination method includes: dividing each of the groups of vertical-dimension beams into a plurality of subgroups of vertical-dimension beams, and dividing each of the groups of horizontal-dimension beams into a plurality of subgroups of horizontal-dimension beams; determining a first stage codebook in accordance with a Kronecker product of each subgroup of vertical-dimension beams acquired by dividing each of the groups of vertical-dimension beams and each subgroup of horizontal-dimension beams acquired by dividing each of the groups of horizontal-dimension beams; and selecting a plurality of columns of beams from the determined first stage codebook using a second stage codebook, and performing phase adjustment to determine a precoding matrix.