The writer considers that there is a large amount of U and Th in the outer core of the Earth. It is these U and Th that provide the energy to drive the movement of materials inside the Earth (especially the movement of the plate tectonic system s). According to the seismic wave data from the upper mantle to lower mantle , the hottest region inside the Earth lies under the center of the Pacific Ocean. Moreove r, the center of the geomagnetic field departs from the center of the Earth at towards the Pacific plate for 400 km, which shows that the center of geo dynamic and correspondingly the center of thermal convection are also closer to the Pac ific plate for 400 km. Therefore, U and Th are richer in the outer core beneath the Pacific plate.  The discovery of natural nuclear reactor in the Precambrian rocks and the research results of the relationship between the mass and luminosity of the pla nets show that nuclear fission can also occur in the outer core of the Earth. The fact that the rocks and xenoliths discovered in the hot plumes in the Pacific O cean has the highest content of noble gases in the Earth, such as 3He, 129Xe,136Xe and 86Kr, which are connec ted cl osely with the nuclear fission of U and Th in origination, also supports this point of view. When nuclear fission occurs , the great heat produced from that will boil the outer core and melt the inner core, which will weaken the geomagnetic field and stop its reversal, namely the ge omagnetic standstill stages. This great heat will also cause the possible Earth exp ansion.