Abstract: In the process of earthquake preparation, stress in the focal area could increase with tectonic stress. When the stress increases to a certain level, the focal area will become unstable. On the basis of this view point, the variations of crustal tectonic stress in Palau Islands area were investigated by using apparent stress in this paper. Meanwhile, the correlation of seismic activity with earth’s rotation was examined. The results indicate that there could be a risk of M_S8.0 occurring in this area in the next two to three years.