A Channel State Information (CSI) feedback method, comprising: performing, by a terminal, channel estimation based on a pilot signal received by the terminal to acquire channel estimation values of A antenna ports for transmitting the pilot signal by a network device ; determining, by the terminal, Q antenna ports based on the channel estimation values of the A antenna ports, where L≤Q≤A, L represents a value of a Rank Indicator (RI) adopted by the network device during transmitting downlink data to the terminal or a value of a RI of a channel determined by the terminal ; and determining, by the terminal, a first-level Precoding Matrix Indicator (PMI) based on the Q antenna ports, and feeding back CSI containing the first-level PMI to the network device, the first-level PMI being used to indicate indices of the Q antenna ports among the A antenna ports for transmitting the pilot signal ; characterized in that the method further comprises the determining, by the terminal, the Q antenna ports based on the channel estimation values of the A antenna ports comprises determining, by the terminal within a range of the number of the antenna ports, all possible combinations of antenna ports, and determining, from all the possible combinations of antenna ports, Q antenna ports capable of providing maximum throughput or capacity of a channel between the terminal and the network device or providing maximum received pilot signal power of the terminal, the throughput or capacity of the channel corresponding to each possible combination of antenna ports or the received pilot signal power of the terminal being determined based on the channel estimation value corresponding to the possible combination of antenna ports. performing, by a terminal, channel estimation based on a pilot signal received by the terminal to acquire channel estimation values of A antenna ports for transmitting the pilot signal by a network device ; determining, by the terminal, Q antenna ports based on the channel estimation values of the A antenna ports, where L≤Q≤A, L represents a value of a Rank Indicator (RI) adopted by the network device during transmitting downlink data to the terminal or a value of a RI of a channel determined by the terminal ; and determining, by the terminal, a first-level Precoding Matrix Indicator (PMI) based on the Q antenna ports, and feeding back CSI containing the first-level PMI to the network device, the first-level PMI being used to indicate indices of the Q antenna ports among the A antenna ports for transmitting the pilot signal ; characterized in that the method further comprises the determining, by the terminal, the Q antenna ports based on the channel estimation values of the A antenna ports comprises determining, by the terminal within a range of the number of the antenna ports, all possible combinations of antenna ports, and determining, from all the possible combinations of antenna ports, Q antenna ports capable of providing maximum throughput or capacity of a channel between the terminal and the network device or providing maximum received pilot signal power of the terminal, the throughput or capacity of the channel corresponding to each possible combination of antenna ports or the received pilot signal power of the terminal being determined based on the channel estimation value corresponding to the possible combination of antenna ports. <EOS>