A data demodulation method, apparatus, and system are presented. The method includes obtaining notification information indicating that user equipment (UE) is in a high-speed moving state; performing time-frequency synchronization processing on first downlink data according to the notification information to obtain second downlink data; and performing demodulation processing on the second downlink data to obtain third downlink data, where in the demodulation processing, inter-transmission time intervals (TTIs) filtering for a channel estimation is not performed, or a filtering coefficient as a weight of a current TTI for a channel estimation is greater than a filtering coefficient as a weight of a TTI that is at the time when the UE is in the non-high-speed moving state for a channel estimation. The demodulation method is applicable to a high-speed scenario for improving a downlink data throughput of the UE.