Abstract: The continuous observation data of the PET gravimeter at the Hailar Earthquake Monitoring Central Station from 2021 to 2023 were taken as the research object. The original continuous gravity data were preprocessed by using the Tsoft software to obtain the gravity residual data. The time-frequency analysis of the gravity residual data was conducted through the HHT method, and the spectral characteristics of the background noise of the continuous gravity data of the station were summarized. It was concluded that the background noise of the continuous gravity observation at the Hailar Station was mainly concentrated in the frequency band of 0.05 - 0.28 Hz, with the dominant frequency being 0.23 Hz. This study aided in identifying the normal observation background and interference characteristics of gravity data, providing a background basis for analyzing seismic anomaly information.