This application provides a signal demodulation method, a signal transmission method, and a related apparatus. The signal demodulation method includes: A terminal device receives a first tracking reference signal from a first transmission reception apparatus of a single frequency network cell; receives a second tracking reference signal from a second transmission reception apparatus of the single frequency network cell, where the first tracking reference signal and the second tracking reference signal occupy different time-frequency resources; receives indication information from the first transmission reception apparatus or the second transmission reception apparatus, where the indication information indicates one or more tracking reference signals for receiving a downlink signal, and the downlink signal includes a demodulation reference signal and downlink data; determines, based on the one or more tracking reference signals for receiving the downlink signal, a first carrier frequency on which the downlink signal is to be received; receives the demodulation reference signal and the downlink data based on the first carrier frequency; and demodulates the downlink data based on the demodulation signal. This can improve data receiving performance. Technical solutions of this application may be applied to a single frequency network scenario, for example, a highspeed railway scenario.