the present invention relates to a channel state information 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 .