A data multiplexing method, comprising: transmitting, by a network-side device, a channel state information-reference signal CSI-RS and a data signal to a terminal, wherein the CSI-RS is used for channel state measurement or beam quality measurement; and sending, by the network-side device, CSI-RS multiplexing indication information to the terminal, wherein the CSI-RS multiplexing indication information is used to indicate whether frequency division multiplexing is performed on the data signal and the CSI-RS, before the sending, by the network-side device, CSI-RS multiplexing indication information to the terminal, comprising: when the CSI-RS is used to perform channel state measurement on the terminal, and an orthogonal frequency division multiplexing OFDM symbol in which the CSI-RS is located has an idle resource, determining that frequency division multiplexing is to be performed on the data signal and the CSI-RS; or when the CSI-RS is used to perform channel state measurement on the terminal, but an OFDM symbol in which the CSI-RS is located does not have an idle resource, determining that frequency division multiplexing is not to be performed on the data signal and the CSI-RS; or when the CSI-RS is used for beam measurement, determining that frequency division multiplexing is not to be performed on the data signal and the CSI-RS. transmitting, by a network-side device, a channel state information-reference signal CSI-RS and a data signal to a terminal, wherein the CSI-RS is used for channel state measurement or beam quality measurement; and sending, by the network-side device, CSI-RS multiplexing indication information to the terminal, wherein the CSI-RS multiplexing indication information is used to indicate whether frequency division multiplexing is performed on the data signal and the CSI-RS, before the sending, by the network-side device, CSI-RS multiplexing indication information to the terminal, comprising: when the CSI-RS is used to perform channel state measurement on the terminal, and an orthogonal frequency division multiplexing OFDM symbol in which the CSI-RS is located has an idle resource, determining that frequency division multiplexing is to be performed on the data signal and the CSI-RS; or when the CSI-RS is used to perform channel state measurement on the terminal, but an OFDM symbol in which the CSI-RS is located does not have an idle resource, determining that frequency division multiplexing is not to be performed on the data signal and the CSI-RS; or when the CSI-RS is used for beam measurement, determining that frequency division multiplexing is not to be performed on the data signal and the CSI-RS. when the CSI-RS is used to perform channel state measurement on the terminal, and an orthogonal frequency division multiplexing OFDM symbol in which the CSI-RS is located has an idle resource, determining that frequency division multiplexing is to be performed on the data signal and the CSI-RS; or when the CSI-RS is used to perform channel state measurement on the terminal, but an OFDM symbol in which the CSI-RS is located does not have an idle resource, determining that frequency division multiplexing is not to be performed on the data signal and the CSI-RS; or when the CSI-RS is used for beam measurement, determining that frequency division multiplexing is not to be performed on the data signal and the CSI-RS.