The invention provides a two-level codebook selection method in an LTE-A (Long Term Evolution-Advanced) system, wherein a first-level codebook code word W1 is multiplied by a second-level codebook code word W2 to obtain a precoding matrix W, and according to different criteria, a user separately selects the W1 and the W2 and feeds back corresponding indexes PMI1 and PMI2. The two-level codebook selection method is applicable to the circumstance that linear and non-linear detectors are used by a receiver end, and under the premise of ensuring low computational complexity, the bit error rate of the system can be greatly decreased. In particular, for the circumstance that non-linear detectors, such as a maximum likelihood detector and a spherical detector, are used by the receiver end, the method can be used for sufficiently exploiting the potential performance advantages of the non-linear detectors. The two-level codebook selection method is applicable to the circumstance that the distance between cross polarised antennas of the transmitting end is the result of dividing the Lambda (the wavelength of transmitted electromagnetic waves) by 2 or the result of multiplying the Lambda by 4, and under both circumstances, the two-level codebook selection method can show high bit error rate performance.