A kind of mechanical source pattern of upwelling mantle material in the process of earthquake preparation is simulated by taking a dilatancy cone cylinder bodyin two-layer medium as a model.The variations of stress and strain as well as displacement in the medium are calculated when the analogous mechanical source of the cone cylinder body changes in different lateral and lengthwise scales as well as taper angle under the condition of layered medium.The results show that the fields of stress and strain as well as displacement in the medium or near the ground surface relate not only to the geometric and physical parameters of upwelling mechanical source,but also to the geometric parameters of layered medium structure.This numerical simulation provides a significant method for explaining why the upper mantle material flows into lower crust and show that the variation of medium structure must be considered for recognizing the distribution of precursor fields related to this kind of seismogenic process.