This application provides a reference signal receiving method, a reference signal sending method, and an apparatus. The reference signal receiving method includes: when a terminal device is out of a first time period, detecting, by the terminal device, a first signal, and determining, based on a detection result of the first signal, whether to use a first reference signal to perform time-frequency tracking and/or channel measurement; and receiving, by the terminal device, a second reference signal when the terminal device is in the first time period, where the first reference signal and the second reference signal are reference signals used for time-frequency tracking and/or channel measurement.