On the basis of dynamic equations for seismic analysis derived from system energy

the seismic response of layered foundation-nonlinear structure system is studied by means of asymptotic method (KBM). The analytical formulas of amplitude-frequency and phase-frequency are obtained. A series of calculating results for different values of foundation parameters are presented in seismic resonant area. And then according to corresponding calculating results

the effect of foundation parameters on seismic properties of structure is analyzed; and the nonlinear dynamic characteristics，such as distortion of resonant area

bifurcation and suddenly jumping of amplitude

as well as the path effect

are discussed. It is indicated that the value change of foundation parameters of the same sort causes remarkable influence on structure dynamic properties

and the calculating error by the current Code of seismic design might be obvious for the analysis of layered foundation- nonlinear structure system. The interaction between soil and structure and nonlinear properties must be considered in order that design parameters are more reasonable and optimal.