Based on the seismic isolation study of the storage tanks,starting with sloshing,rigid motion and fluid-structure coupling motion of the tanks,the dynamic response theory of hydrodynamic pressure,sloshing wave,base shear and overturning moment of the storage tanks was studied.Rational potential function was selected according to the velocity potential and boundary conditions that the structure of storage tanks satisfied.The equivalent mass and the relative height of mass center were given by using the same base shear and overturning moment of the liquid tank system and equivalent mechanical model when subjected to the same ground motion,and a three centralized particles mechanics analysis model was established.The simplified expressions of sloshing wave,base shear and overturning moment were given as well.The motion equation of the seismic system was established according to Harmilton principle.The earthquake responses of 2 × 104 m3and 15 × 104 m3 isolated and non-isolated tanks were analyzed by adopting the time history method.The numerical result shows that the base isolation seismic system exhibits good performance of seismic isolation.