Abstract: Liquid storage tanks are vulnerable to excessive base shear force, liquid sloshing, and isolation displacements during earthquakes, while conventional isolation methods show limited effectiveness in controlling multiple responses. Theoretical and numerical studies have demonstrated that inerter-based isolation system performs better for storage tanks, but experimental validation is still lacking. This study proposes an inerter-based synergistic isolation system consisting of laminated rubber bearings, elastic sliding bearings and inerters, and further develops a theoretical model with corresponding semi-analytical solutions. Based on this framework, a multi-objective design method guided by the target input energy ratio is proposed to achieve synergistic control of base shear force, sloshing height and isolation displacement. Numerical simulations and shaking table tests are conducted to validate the effectiveness of the proposed method, with comparative analyses performed against base-fixed tank system and conventional combined isolation tank systems. Results indicate that the proposed system can significantly reduce input energy and key seismic responses while maintaining the operational integrity of the tanks, and provides a wider control bandwidth with improved robustness. This study offers an efficient and non-intrusive solution for the seismic protection of liquid storage tanks.