A time division duplex channel information obtaining method, comprising: sending, by a base station, a downlink reference signal to a terminal, wherein the downlink reference signal is used by the terminal to obtain second channel information, and the second channel information is used to indicate channel state matrix information of a second subset of channels between the base station and the terminal; receiving, by the base station, an uplink reference signal from the terminal, wherein the uplink reference signal is used by the base station to obtain first channel information, and the first channel information is used to indicate channel state matrix information of a first subset of channels between the base station and the terminal, wherein channels of the first subset of channels are channels formed between one antenna of the terminal and each antenna of the base station, and the second subset of channels are channels formed between other antennas of the terminal than the one antenna of the terminal and each antenna of the base station, and the first subset and second subset of channels form a set of channels between the base station and the terminal; obtaining, by the base station, the first channel information from the uplink reference signal; and receiving, by the base station, the second channel information from the terminal, wherein a rank of the channels between the base station and the terminal is greater than 1 and less than a maximum value of a rank of the channels between the base station and the terminal, and wherein the second channel information comprises partial channel state matrix information of a subset of the second subset of channels between the base station and the terminal and the second channel information further comprises channel quality indicator CQI information and/or rank indicator RI information, and wherein the first channel information and the second channel information are used to obtain channel state matrix information of the first subset and the subset of the second subset of channels between the base station and the terminal; receiving, by the base station from the terminal, a sequence number of a transmit antenna corresponding to the uplink reference signal, wherein the sequence number of the transmit antenna is used to adjust a sequence of rows or columns of the channel state matrix information of the set of channels between the base station and the terminal. sending, by a base station, a downlink reference signal to a terminal, wherein the downlink reference signal is used by the terminal to obtain second channel information, and the second channel information is used to indicate channel state matrix information of a second subset of channels between the base station and the terminal; receiving, by the base station, an uplink reference signal from the terminal, wherein the uplink reference signal is used by the base station to obtain first channel information, and the first channel information is used to indicate channel state matrix information of a first subset of channels between the base station and the terminal, wherein channels of the first subset of channels are channels formed between one antenna of the terminal and each antenna of the base station, and the second subset of channels are channels formed between other antennas of the terminal than the one antenna of the terminal and each antenna of the base station, and the first subset and second subset of channels form a set of channels between the base station and the terminal; obtaining, by the base station, the first channel information from the uplink reference signal; and receiving, by the base station, the second channel information from the terminal, wherein a rank of the channels between the base station and the terminal is greater than 1 and less than a maximum value of a rank of the channels between the base station and the terminal, and wherein the second channel information comprises partial channel state matrix information of a subset of the second subset of channels between the base station and the terminal and the second channel information further comprises channel quality indicator CQI information and/or rank indicator RI information, and wherein the first channel information and the second channel information are used to obtain channel state matrix information of the first subset and the subset of the second subset of channels between the base station and the terminal; receiving, by the base station from the terminal, a sequence number of a transmit antenna corresponding to the uplink reference signal, wherein the sequence number of the transmit antenna is used to adjust a sequence of rows or columns of the channel state matrix information of the set of channels between the base station and the terminal.