In this study, a numerical solution for a 2-D fault site model under incident P waves using the explicit finite element method combined with transmission of artificial boundary condition was derived. The distribution rules of peak ground acceleration (PGA) and the spectrum characteristics influenced by fault characteristics such as width and shear wave velocity of the fault and the incidence angle of the seismic waves were discussed. Numerical simulations shown that transform SV waves developed in the low velocity fault zone (LVFZ) when it struck by external incident P waves, and many trapped waves obviously developed in it. This result implied that the external incident seismic radiation congregated in the LVFZ, and the agglomeration effect increased with the increased width and decreased shear wave velocity of the LVFZ. Vertical LVFZs blocked the spread of oblique incident P waves, and the isolation effect decreased with the increased incidence angle of P waves. The seismic response of a variety of LVFZ models with different width and shear wave velocity struck by external vertically incident P waves was determined, and the results implied that the ground motion amplification characteristics in the near fault zone site are frequency dependent. The higher frequency components of ground seismic waves are obviously amplified by LVFZs with narrower widths and higher shear wave velocities, while the lower frequency components of ground seismic waves are obviously amplified by LVFZs with wider widths and lower shear wave velocities. In other words, the site amplification coefficient is frequency dependent, such that the widening the width or decreasing the shear wave velocity of fault fracture zone, the predominant frequency of a larger site amplification coefficient is becoming lower.