Example reference signal transmission methods and apparatus are described. In one example method, a base station divides a transmission bandwidth into a plurality of frequency domain units, and sends reference signal sending configuration information to a terminal. The terminal transmits a reference signal on one or more frequency domain units. The one or more frequency domain units and another frequency domain unit form a part of the transmission bandwidth supported by the base station. The terminal sends the reference signal on the one or more frequency domain units to the base station based on the reference signal sending configuration information.