A method for measuring Channel State Information, CSI, comprising steps of: transmitting (S701), by a network side device, a group of reference signals which have been beamformed to a User Equipment, UE, so as to enable the UE to measure the reference signals, each reference signal in the group of reference signals corresponding to a space in a sector, wherein reference signals in each sector correspond to different identifiers; determining (S702), by the network side device, quality information corresponding to each reference signal in accordance with the identifier and quality information from the UE; determining (S702), by the network side device, whether or not the beamforming mode for each reference signal is to be adjusted in accordance with the quality information corresponding to each reference signal; determining (S702), by the network side device, each space in the spaces corresponding to the reference signals with the best quality information, in the case that the beamforming mode for each reference signal needs to be adjusted; and adjusting (S702), by the network side device, the beamforming mode for the reference signal corresponding to each space, taking the reference signals with the best quality information as a group of reference signals, and transmitting the group of reference signals which have been beamformed to the UE, the method is characterized in that the network side device determines that a channel for transmitting reference signals to the UE is instable and the beamforming mode needs to be adjusted, in the case that changing speed of the channel exceeds a predetermined value, and otherwise, determines that the beamforming mode does not need to be adjusted. transmitting (S701), by a network side device, a group of reference signals which have been beamformed to a User Equipment, UE, so as to enable the UE to measure the reference signals, each reference signal in the group of reference signals corresponding to a space in a sector, wherein reference signals in each sector correspond to different identifiers; determining (S702), by the network side device, quality information corresponding to each reference signal in accordance with the identifier and quality information from the UE; determining (S702), by the network side device, whether or not the beamforming mode for each reference signal is to be adjusted in accordance with the quality information corresponding to each reference signal; determining (S702), by the network side device, each space in the spaces corresponding to the reference signals with the best quality information, in the case that the beamforming mode for each reference signal needs to be adjusted; and adjusting (S702), by the network side device, the beamforming mode for the reference signal corresponding to each space, taking the reference signals with the best quality information as a group of reference signals, and transmitting the group of reference signals which have been beamformed to the UE, the method is characterized in that the network side device determines that a channel for transmitting reference signals to the UE is instable and the beamforming mode needs to be adjusted, in the case that changing speed of the channel exceeds a predetermined value, and otherwise, determines that the beamforming mode does not need to be adjusted. <EOS>