To provide base isolation design theory support of vertical storage tank, based on existing elastic theory seismic model,introducing the base isolation measures, the base isolation mechanical model was established,which was convenient to engineering design staff, at the same time,base isolation mechanical model was compared to elasticity theory three-mass tank isolation mechanical model which was author put. For 1.5×10⁵ m³ vertical storage tanks, isolation layer using the equivalent linear model, selecting 0.40g El-Centro seismic wave as the ground motion input, the equations of motion using numerical integration method, the model parameters and seismic response were analyzed. The results showed that: several elastic theory tank isolation model mass and height parameters were similar,storage tank design could be compared with reference to calculation. Convective mass of several models more than 70％ total mass,it should be give attention. Isolation reduces the earthquake response of elastic impulse component, while long period convective component plays a leading role. From the actual situation, elasticity theory three-mass tank isolation mechanical model of author was feasible and applicable.