Salt rock is widely recognized as an excellent medium for constructing CAES (compressed air energy storage) reservoirs due to its favorable rheological properties, low permeability, and self-healing characteristics. However, salt formations in China are characterized by thin salt layers and numerous interlayers, which generate a significant amount of sediment during the process of water-soluble cavity creation.With the W salt cavern reservoir in Tai’an, Shandong Province as the research context. The effect of sediment on the cavern is equivalently represented as a gradient soil pressure, and a computational model related to soil pressure was established based on the point cloud cavity morphology characterized by 3D seismic exploration. Using FLAC^3D software, the impact of sediment on the stability of CAES caverns and surface subsidence was investigated through numerical simulations comparing two scenarios: with and without sediment. The results indicate that sediment effectively limits the development of the plastic zone in the surrounding rock and reduces displacement around the cavity. The reduction in cavity wall displacement ranges from approximately 0.08 m to 0.12 m. After 30 years of operation, the volume shrinkage of the sediment-containing cavity is 1.3×10⁴ m³ less than that of the cavity without sediment, corresponding to a 1.17% reduction in shrinkage rate. Additionally, surface subsidence is reduced by 5.45 mm. These findings demonstrate that the presence of sediment enhances cavity stability and contributes to the long-term operational efficiency and economic viability of the CAES reservoir.