The present invention is applicable in the field of communications. Provided are a method, user equipment (UE), base station, and system for triggering a channel state information (CSI) non-periodic feedback. The method comprises: the UE receiving a dynamic signaling, where the dynamic signaling is used for indicating that the UE needs to feedback a CSI measurement hypothesis set of a first service cell, or, the CSI measurement hypothesis set of a service cell set, where the CSI measurement hypothesis set comprises at least one measurement hypothesis, where the one measurement hypothesis comprises at least one measurement reference signal, and where the service cell set comprises at least one service cell; and, feeding back, on the basis of the dynamic signaling, the CSI of the first service cell and based on the CSI measurement hypothesis set or the CSI of the service cell set and based on the CSI measurement hypothesis set. The present invention is capable of effectively solving the problem in a CoMP system of triggering the CSI non-periodic feedback based on various CSI measurement hypotheses, thus reducing feedback overhead.