The present invention discloses a method, a device, and a system for measuring channel state information, which relate to the communications field. The method includes: transmitting, by a base station BS, multiple sets of channel state indication reference signal CSI-RS resources; and notifying a user equipment UE of an aggregation mode of the CSI-RS resources, so that after the UE aggregates the multiple sets of CSI-RS resources according to the aggregation mode of the CSI-RS resources to form a measurement source, the UE performs CSI measurement according to a channel corresponding to CSI-RS ports on the measurement source.