As a stable compound of C and Si, silicon carbide has a lattice structure consisting of two closely arranged sublattices. Each Si (or C) atom is bound to the surrounding C (Si) atom by a strong oriented tetrahedral sp3 bond. Although SiC has a strong tetrahedral bond, the stacking fault formation energy is very low. This feature determines the polytype phenomenon of SiC. It has been found that SiC has more than 250 polytypes, The stacking order of C/Si diatomic layers of each polymorph is different. The most common polymorphs are cubic close packed 3C SiC and hexagonal close packed 4H, 6H SiC. Different polytypes have different electrical and optical properties. The band gap width of SiC is 2-3 times that of Si, the thermal conductivity is about 4.4 times that of Si, the critical breakdown electric field is about 8 times that of Si, and the saturated drift velocity of electrons is twice that of Si. These properties of SiC make it the preferred material for high frequency, high power, high temperature resistant and radiation resistant semiconductor devices，which can be used in extreme environments of high-power electronic converters and automotive motors. In addition, the radiation wavelength of the light-emitting diodes prepared with SiC can cover the band from blue light to purple light, which has broad application prospects in the fields of optical information display systems and optical integrated circuits.