The human has curiosity for unknown things, such as the inner structure of human body or the Earth. Modern medicine adopts “Computerized Tomography” (CT for short) technology to probe into the human body. Via this technology, plenty of data have been obtained for analysis made on the human body. Likewise, the Earth is an opaque object in the visible light. Enlightened by CT made on the human body, the human can probe into the inner structure of the Earth with the CT-like technology. And this technology is geophysics which, just as its name implies, is used to study the Earth by physical principles. The basis on which the geological problems are solved with geophysical detection results is physical properties of rock. The Earth consists of all kinds of rock and the fluids contained in it. Every kind of rock has its corresponding parameters of its physical properties, which is the basis on which various mediums can be differentiated with geophysical methods. Geophysics has been under development for nearly one hundred years, and people have invented a series of commonly-used geophysical detection methods which are represented by stress gravity prospecting, magnetic prospecting, seismic prospecting and electrical prospecting respectively against density difference, magnetic susceptibility difference, speed difference and electroconductibility difference inside the Earth.