The present invention belongs to the field of communications technologies, and discloses a channel state information CSI feedback method and an apparatus. The method includes: determining a codebook of at each transport layer CSI of user equipment UE, where the codebook of the CSI at each transport layer of the UE is: W=W1×W2, an element Xi in W2 is a weighting coefficient corresponding to each codeword in W1, and i is an integer greater than or equal to 1 and less than or equal to K; determining a quantity Ni of bits occupied by a quantized value of an ith element in W2, where quantized values of at least two elements in W2 occupy different quantities of bits; and feeding back the quantized value of the ith element to a network device based on Ni.