The embodiments of the present invention disclose a method and an apparatus for sub-sampling of a codebook in the LTE-A system where a precoding matrix W is a product of two matrices W1 and W2, i.e. W=W1W2, codebooks for W, W1 and W2 are denoted as C, C1 and C2 respectively, and r indicates a rank. The method includes sub-sampling the codebook C such that the sub-sampled codebook C has a size of equal to or less than 4 bits. In the sub-sampling, codewords evenly distributed in the codebook C are extracted, where some or all of the codewords are in a form of discrete Fourier transform (DFT) vector to be suitable for evenly linear arrays, and the other codewords are suitable for cross-polarized linear arrays.