A method for feeding back downlink channel feedback information of a Multiple Input Multiple Output, MIMO, communication system, comprising: calculating a multi-user channel quality indication error of a user in the system by the user based on a signal to noise ratio, wherein the multi-user channel quality indication error is used to reflect the difference in channel quality indication between the situation of multi-user multiple input multiple output transmission and the situation of single user multiple input multiple output transmission of the user; and adding the multi-user channel quality indication error to the downlink channel feedback information including a pre-coding matrix indication and a channel quality indication, and feeding the same back to a base station for scheduling, wherein the pre-coding matrix indication corresponds to one pre-coding matrix in 2-antenna and 4-antenna base station configurations; and the pre-coding matrix indication comprises a first pre-coding matrix indication corresponding to a measured channel state over a transmission bandwidth of the downlink channel and a second pre-coding matrix indication corresponding to sub-band information of a measured channel state over a sub-band in the feedback bandwidth of the downlink channel in an 8-antenna base station configuration; wherein the calculating the multi-user channel quality indication error comprises: calculating the multi-user channel quality indication error based on the signal to noise ratio of the user, further comprises: measuring a channel state of the user to obtain a channel information matrix and the signal to noise ratio; calculating a quantization error according to the channel information matrix and a pre-coding matrix obtained based on the channel information matrix; finding a channel with the minimum interference level from channels orthogonal to the channel of the user; calculating the signal to noise ratio of the user in the situation of multi-user multiple input multiple output transmission by using the quantization error, the minimum interference level and the measured signal to noise ratio; and calculating the multi-user channel quality indication error according to the measured signal to noise ratio and the calculated signal to noise ratio of the user in the situation of multi-user multiple input multiple output transmission. calculating a multi-user channel quality indication error of a user in the system by the user based on a signal to noise ratio, wherein the multi-user channel quality indication error is used to reflect the difference in channel quality indication between the situation of multi-user multiple input multiple output transmission and the situation of single user multiple input multiple output transmission of the user; and adding the multi-user channel quality indication error to the downlink channel feedback information including a pre-coding matrix indication and a channel quality indication, and feeding the same back to a base station for scheduling, wherein the pre-coding matrix indication corresponds to one pre-coding matrix in 2-antenna and 4-antenna base station configurations; and the pre-coding matrix indication comprises a first pre-coding matrix indication corresponding to a measured channel state over a transmission bandwidth of the downlink channel and a second pre-coding matrix indication corresponding to sub-band information of a measured channel state over a sub-band in the feedback bandwidth of the downlink channel in an 8-antenna base station configuration; measuring a channel state of the user to obtain a channel information matrix and the signal to noise ratio; calculating a quantization error according to the channel information matrix and a pre-coding matrix obtained based on the channel information matrix; finding a channel with the minimum interference level from channels orthogonal to the channel of the user; calculating the signal to noise ratio of the user in the situation of multi-user multiple input multiple output transmission by using the quantization error, the minimum interference level and the measured signal to noise ratio; and calculating the multi-user channel quality indication error according to the measured signal to noise ratio and the calculated signal to noise ratio of the user in the situation of multi-user multiple input multiple output transmission.