A method for providing feedback of Channel State Information, CSI, comprising: selecting, by a terminal, one or more Channel State Information-Reference Signal, CSI-RS, resources in a prescribed sub-band or one or more CSI-RS ports in the prescribed sub-band, from a CSI-RS resource set configured by a base station according to downlink channel information; measuring, by the terminal, one or more Channel Quality Indicators, CQIs, according to the one or more selected CSI-RS resources or according to the one or more selected CSI-RS ports, and according to a pre-coding matrix set corresponding to the one or more selected CSI-RS resources or corresponding to the one or more selected CSI-RS ports, wherein the pre-coding matrix set comprises one or more pre-coding matrixes; and providing, by the terminal, feedback of the one or more CQIs, and feedback of indication information of the one or more selected CSI-RS resources or feedback of indication information of the one or more selected CSI-RS ports; characterized in that, each of one or more physical resources in the prescribed sub-band corresponds to one of the one or more pre-coding matrixes in the pre-coding matrix set; an i-th physical resource in the prescribed sub-band corresponds to a k-th pre-coding matrix in the pre-coding matrix set, wherein k=i mod K, wherein i=0,1,2...N, k=0,1,2,3,...,K-1, K is the number of the one or more pre-coding matrixes in the pre-coding matrix set, and N is the number of the one or more physical resources in the sub-band; or, k=ceil(i/v) mod K, wherein ceil(i/v) represents a minimum integer no less than i/v, v= Rank Indicator, RI, or v is the number of one or more antenna ports, i=0,1,2...N, k=0,1,2,3,...,K-1, K is the number of the one or more pre-coding matrixes in the pre-coding matrix set, and N is the number of the one or more physical resources in the sub-band; wherein the one or more physical resources are one or more Resource Elements, REs, one or more sub-carriers, one or more Physical Resource Blocks, PRBs, or one or more PRB sets. selecting, by a terminal, one or more Channel State Information-Reference Signal, CSI-RS, resources in a prescribed sub-band or one or more CSI-RS ports in the prescribed sub-band, from a CSI-RS resource set configured by a base station according to downlink channel information; measuring, by the terminal, one or more Channel Quality Indicators, CQIs, according to the one or more selected CSI-RS resources or according to the one or more selected CSI-RS ports, and according to a pre-coding matrix set corresponding to the one or more selected CSI-RS resources or corresponding to the one or more selected CSI-RS ports, wherein the pre-coding matrix set comprises one or more pre-coding matrixes; and providing, by the terminal, feedback of the one or more CQIs, and feedback of indication information of the one or more selected CSI-RS resources or feedback of indication information of the one or more selected CSI-RS ports; characterized in that, each of one or more physical resources in the prescribed sub-band corresponds to one of the one or more pre-coding matrixes in the pre-coding matrix set; an i-th physical resource in the prescribed sub-band corresponds to a k-th pre-coding matrix in the pre-coding matrix set, wherein k=i mod K, wherein i=0,1,2...N, k=0,1,2,3,...,K-1, K is the number of the one or more pre-coding matrixes in the pre-coding matrix set, and N is the number of the one or more physical resources in the sub-band; or, k=ceil(i/v) mod K, wherein ceil(i/v) represents a minimum integer no less than i/v, v= Rank Indicator, RI, or v is the number of one or more antenna ports, i=0,1,2...N, k=0,1,2,3,...,K-1, K is the number of the one or more pre-coding matrixes in the pre-coding matrix set, and N is the number of the one or more physical resources in the sub-band; wherein the one or more physical resources are one or more Resource Elements, REs, one or more sub-carriers, one or more Physical Resource Blocks, PRBs, or one or more PRB sets.