Embodiments of the present disclosure provide a channel state information (CSI) sending method, a CSI receiving method, a terminal, and a base station. The terminal selects a target CSI process from N CSI processes. The terminal sets a CSI reporting mode corresponding to the target CSI process, and sends, based on the CSI reporting mode, a CSI corresponding to the CSI process. The terminal can set a CSI reporting mode corresponding to a CSI process, and send, based on the set CSI reporting mode, a CSI corresponding to the CSI process. However, in the prior art, only the base station configures a CSI reporting mode corresponding to each CSI process. Therefore, flexibility is increased.