For these port backfilling land platforms formed by sands built on soft soil foundation,its ground condition is special,which consists dense sand layer on top and with soft soil layers underneath.An analysis model is established by using the time-domain nonlinear analysis method of one-dimensional seismic ground response analysis software DEEPSOIL,and 10 sets of seismic acceleration records are selected as input ground motion to analyze the seismic response of this special ground.The results show that the soft soil layer will produce large shear strain under the action of strong earthquake，which fully utilizes hysteresis damping and dissipates seismic energy.The seismic ground motion decreases rapidly during the upward transmission in the soft soil layer,which means that the soft soil layer has obvious absorptio and isolation effects to seismic.