A reference signal sending method and a communications device are provided. The reference signal sending method includes: generating, by a first device, a tracking reference signal, where the tracking reference signal corresponds to a Demodulation Reference Signal (DMRS) port that is used by the first device when the first device sends data to a second device; mapping, by the first device, the tracking reference signal to a time-frequency resource that is used by the first device when the first device sends the data to the second device through the DMRS port, where the tracking reference signal is mapped to at least two modulation symbols on a same frequency resource in one transmission slot; and sending, by the first device, the tracking reference signal mapped to the time-frequency resource to the second device.