The relationship between the 2008 M8.0 Wenchuan Earthquake and the earthrotation is analyzed. A new view of earthquake is presented. A earthquake results from rate change of the earthrotation. The earth crust consists of different size block sand of different mass. , ocean blocks are thin and light, and continental blocks are thick and heavy. When the earthrotation rate changes, different blocks have different velocities. The waters differences result in bump in gorrubbing among blocks. That is earthquake. The energy of an earthquake results from the power differences of block bump ingorrubbing.