In order to improve the solution accuracy and modeling efficiency of 2.5D finite element numerical method，the dynamic response characteristics of ground system under moving load are addressed. The basic rules in selecting computing range and meshing are established. Moreover，the effects of ground stratification on the wave field and wave absorption capacity of boundaries are evaluated. Finally，the modeling approach which can avoid the effect of boundary strictly is suggested. The results indicate that the effect of reflection wave on the results can be overlooked once the computing range fits the requirement of low frequency vibration（about 60 m），and radial mesh can be used in modeling and the minimum mesh size should meet the requirement of high frequency vibration（about 0.5-1.0 m）. There is no wave propagation when the moving speed of load is lower than the Rayleigh wave velocity of ground and the fixed boundary is suggested. In addition，the influence of reflected wave can be completely avoided by cutting the local computation range when the moving speed of load is higher than the Rayleigh wave velocity of ground. In that condition，the half-width and longitudinal space range of model should be confirmed following the geometric relation related to the Mach cone angle and the full length of the train. Furthermore，the layered interface at the load influence depth will disturb the wave filed of ground. Wave will accumulate in the soft soil and multiple Mach cones will occur after the loading point when the ground is covered with soft soil or soft interlayer.