The hall sensor is a magnetic field sensor made according to the Hall effect. The Hall effect is a kind of magnetoelectric effect, a phenomenon that Hall (a.h.hall,1855-1938) discovered in 1879 while studying the conductive mechanism of metals. Later, it was found that semiconductors, conductive fluids and so on also have this effect, and the Hall effect of semiconductors is much stronger than metal, the use of this phenomenon made of a variety of hall components, widely used in industrial automation technology, testing technology and information processing. Hall effect is the basic method to study the properties of semiconductor materials. The hall coefficient, which is determined experimentally, can determine the conductive type, carrier concentration and carrier migration rate of semiconductor materials and other important parameters.