Passive pile is a kind of pile deformed due to horizontal movement of soil. To study the deformation behavior of passive pile in both indoor experiment and numerical calculation, a horizontal displacement is normally applied on the model boundary (as a displacement boundary condition) to form a displacement field of soil. However, various distances between the position where horizontal displacement applied (usually the model boundary) and the location of passive pile are chosen by different researchers. According to an embankment field case, the loading position of horizontal displacement is analyzed using one univariate parameter in finite element method. The results show that the deformation of the pile decreases with increasing the distance between loading position and the location of passive pile, which indicates that stress dispersion occurs obviously in the soil after applying the displacement boundary condition. When the distance is less than 5.5 times of the pile diameter, there is much more stress required to achieve the same level of displacement at the model boundary. The distance from loading position to the pile location is also discussed, and it is found that the reasonable distance is in the range of 5-8 times of pile diameter.