The present disclosure provides a CSI feedback method, a CSI feedback device and a CSI feedback system. The CSI feedback method includes steps of: configuring, by a network side device, a first downlink channel measurement pilot for a UE; and receiving, by the network side device, first PMI information fed back by the UE. The first PMI information is acquired by the UE based on measurement of the first downlink channel measurement pilot and second PMI information. A dimension represented by the first PMI information is different from a dimension represented by the second PMI information.