A method for acquiring channel state information is disclosed in the present invention, including: a user equipment (UE) reporting codebook index information and information about the total number of layers to a base station (eNB), wherein the codebook index information includes one of the following information: class 2 codebook index l; and class 1 codebook index i and index parameter j; and after receiving the codebook index information and information about the total number of layers sent by the UE, the base station obtaining a codeword in the manner of inquiring of a preset codebook list or in the manner of inquiring of the preset codebook list in conjunction with calculation according to the codebook index information and information about the total number of layers. A system for acquiring channel state information is also disclosed in the present invention.