The present invention relates to a channel state information (CSI) feedback method and apparatus in a large-quantity antenna system. An embodiment provides a method used in a UE of a large scale antenna system, including: detecting a downlink channel; determining, according to a multipath propagation model, a channel response of a first number of strong propagation paths, where the channel response of each propagation path is determined as a matrix related to the following time-varying parameters: an arrival direction, time to arrive, and a path amplitude; and feeding back the first number and indication information of the time-varying parameters of the first number of strong propagation paths. By using the sparsity of channels of the large-quantity antenna system, the present invention reduces a feedback payload and maintains at least equal system performance.
