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Based on the explicit FE method and parallel computing cluster platform of ABAQUS, a large-scale two-dimensional (2D) nonlinear analytical model for a multi-geomorphic composite site consisting of valley flat, terraces, undulating hilly terrain was established by considering the inhomogeneity of ground soils and influence of terrain change. Nonlinear seismic effect characteristics of the composite site were analyzed, including the peak ground acceleration (PGA), spectral acceleration, duration and acceleration transfer functions. The main results demonstrated that: (1) the PGA of different observation points on the ground surface vary with each other, which was caused by the terrain differences. For the same input motions, the ground surface PGA of valley flat area show obviously larger than that of the first terrace area. (2) the horizontal spectral acceleration of ground surface appears a double-peak or multi-peak phenomena, the spectra shape peak moves to a larger period in the floodplain area compared with that in first terrace area and the period difference comes to be from 0.05s to 0.25s. (3) the sensitive frequency band of seismic site response was 0.5Hz to 1.75Hz, when the frequency is lower than 0.2Hz or higher than 2Hz, the seismic amplification characteristics is not apparent. （4）PGA exhibits spatial variation characteristics which varies in both lateral and depth directions, and there is a non-monotonic decreasing characteristic with soil depth, greater motion amplification and focusing effect of some shallow soil layers were found. In some degree, the 2D results can reflect nonlinear site effect and the influence of lateral heterogeneity of soils on seismic wave propagation.