Abstract：On the basis of system energy，the dynamic equations of nonlinear foundation-structure system are derived from Lagrange equation. The asymptotic solution and corresponding calculation results of amplitude- frequency are presented in seismic resonant area by means of asymptotic method (KBM)，and then the influence of foundation parameters on properties of structure amplitude-frequency is analyzed. It is indicated that structure response emerges complex nonlinear properties along with the change of foundation parameters，such as distortion of resonant area，amplitude catastrophe，path effect and hysteresis，and there is the unstable resonant area between tow points of catastrophe. The value change of parameters of the same foundation type causes remarkable influence on structure dynamic properties. The calculation error by the current code of seismic design might be obvious for the analysis of nonlinear foundation-structure system. The nonlinear properties must be considered in order that design parameters are more reasonable and optimal.
