Embodiments of the present application provide a channel state information feedback method, device, and system. The method includes: generating an uplink signal, where the uplink signal carries information for identifying multiple codewords and weights of the codewords; and transmitting the uplink signal to a base station (BS), so that the base station estimates a downlink channel based on the multiple codewords and weight information of the codewords in the uplink signal. In the embodiments of the present application, a user equipment UE side reports multiple codewords and weight information of the multiple codewords. This can resolve a problem in the prior art that precision of downlink channel estimation performed by a BS side is relatively low because only a single codeword is reported, and can effectively enhance precision indicated by channel information, without increasing complexity of a codebook design and implementation.