Abstract: Water resources are becoming increasingly scarce worldwide due to population growth and economic development. The overexploitation of groundwater is a global concern, especially in coastal areas where interaction with seawater adds complexity. The high-intensity mining of underground brine in the coastal region of Laizhou Bay, China, has resulted in significant alterations to the groundwater flow field. However, there is a lack of research on how to assess the impact of tides on groundwater levels in such high-intensity brine mining conditions. This study aims to investigate the influence of tidal action on groundwater levels under brine mining conditions using frequency analysis and singular spectrum analysis. The findings demonstrate that underground brine mining is the primary factor driving long-term changes in groundwater levels. Both frequency analysis and wavelet coherence analysis confirm that tidal action has a significant effect on groundwater levels, particularly with 12-hour and 24-hour periodic changes. Moreover, different tidal patterns can be accurately identified based on frequency changes. Singular spectrum analysis effectively captures the impact of tidal variations on groundwater levels. The fluctuations in groundwater level caused by tidal changes in the phreatic layer amount to approximately 11.04% of the tide itself, accounting for 7.89% of the maximum water level change observed during the study period. Similarly, the fluctuations in groundwater level caused by tidal changes in the first confined aquifer amount to approximately 36.80% of the tide itself, accounting for 14.28% of the maximum water level change during the observation period.