In this paper, the general characteristics of the Earth rotation variation and the possible geophysical excitation sources are briefly reviewed. The relations between the decadal fluctuations of the Earth rotation and the core mantle coupling is highlighted. Several possible mechanisms of the core mantle coupling are introduced. The detection of seismic waves is essential to our understanding of the Earth’s interior. In order to study and finally affirm various phenomena and the corresponding geophysical excitation factors, it is very important to comprehensively analyze the information from space geodesy, gravitational measurements and paleogeomagnetic records as well as results from geophysical studies of theories and models.