The main parameters and microscopic phenomena of the four particular earthquakes occurred in the area of the Sanxia area have been introduced in this paper. These earthquakes seem to have two macroscopic epicenters of which the cause of the formation must be much complicated. The area of the Three Gorges is located in the gravity gradient zone in the east of China and the Moho here is rather declivitous. Thus, the single abnormal region of seismic intensity at a distance from the epicenters may occur because seismic reflection waves are focused and reflected by the Moho discontinuity.