A reference signal sending or receiving method includes: determining, by the network device, a plurality of resource elements REs used to carry a first CSI-RS, where the plurality of REs are distributed in a plurality of resource units, and in each resource unit, a plurality of REs used to carry the first CSI-RS are located on a plurality of subcarriers in a same symbol, values of the first CSI-RS carried on at least two REs are different, and values of the first CSI-RS are loaded to the plurality of REs in the resource unit by using a first multiplex code; and sending, by the network device, the first CSI-RS to the terminal device by using the plurality of REs.