Abstract: A finite element model of 160 000 m3 LNG reservoir tank was established to do the numerical simulation of the structure response，the formula of additional mass standard was deduced，the liquid-solid coupling effect in the dynamic response could be characterized by additional mass method，based on which the structure response of LNG reservoir tank under the action of earthquake was analyzed and then the stress time-history was achieved． According to the characteristics that the structure response of LNG reservoir tank was complicated by high degree nonlinearity，the simulation of the complex relationship between stochastic parameters and system response could be done based on stochastic response surface method，and the complex relationship was transformed to the function of standard random variables by Hermite polynomial． Thereby，limit state equation was established to obtain the reliability corresponding to the structural failure criteria．