Disclosed are a channel state information feedback and acquisition method and device. The application comprises: acquiring, by a terminal, a first-dimension downlink reference signal resource, S second-dimension downlink reference signal resources and a first corresponding relationship of the above configured by a network device; measuring, by the terminal and according to the first-dimension downlink reference signal resource, a first-dimension downlink reference signal, and selecting, by the terminal and according to the measured first-dimension PMI and the first corresponding relationship, a resource for measuring a second-dimension downlink reference signal, measuring, according to the resource, the second-dimension downlink reference signal, and feeding back channel state information, wherein the second-dimension reference signal is transmitted after forming a first-dimension beamforming weight. The present application enables acquisition of channel state information between a network device and a terminal, and adjustment of the first-dimension beamforming weight for forming the second-dimension reference signal according to the PMI fed back by the first-dimension.