This study uses the soil parameter reduction coefficients to model the seismic pile responses affected by liquefied soils. One dimensional wave equation analyses were conducted for the solutions. Based on the bore-hole data and nearby seismic record, the soil parameter reduction coefficients of liquefied layers can be obtained through a pre-analysis for liquefaction potential of the site. The reduction coefficients were used to reduce the soil modulus for liquefied soils, and the lumped mass analysis is performed to obtain the free-field response of the site. The ground deformations are superimposed onto the pile elements for discrete wave equation analysis, and the non-linear pile responses can be simulated through the modified Bouc-Wen model. Thus the deformations and failure mechanism of the pile are able to investigate. This analysis is also validated by linear ABAQUS analysis and the case studies of pile failure due to earthquake in Japan. 　　The results of this study are concluded as follows: (1) In the liquefied layers, the sharp changes of soil parameter reduction coefficients may cause greater internal forces to occur and the failure of pile. (2) Largest pile displacements would occur at the pile head. A very large bending moment of the pile that exceeds the ultimate moment of the pile would occur at the interface between the liquefied layer and the underneath non-liquefiable layer. Damage pattern might occur in many ways. (3) For liquefaction potential analyses based on SPT-N values, it is found that the NJRA (1996) method is the most conservative one, where the T&Y (1983) method is the optimistic one. The NCEER (1997) method ends up in the median; In the analyses, if the thickness of liquefied layers are about the same, the reduction coefficient will affect significantly the internal forces of the pile, and relatively insignificant to the pile displacements. (4) For the influence factors on the pile behavior, the ground stiffness has the most influence. PGA is the 2nd significant one. Ground water table and fine content of soil have smaller effects. Furthermore, soil spring and damping have minor influences on pile’s deformations, but they are sensitive to the internal pile forces. (5) The NCEER method is found to provide comparative results to the field observations of the case studies, therefore it is suggested to use NCEER in the corresponding analysis. (6) The reduction coefficient model is rather simple to simulate degradation of the soil modulus, it is conjunct with the liquefaction potential analysis of the site and coincident with common geotechnical engineering practice. This model would be very helpful to the seismic performance analysis of the pile foundations.