As a well-known cathode material, rare earth hexaboride (RB6) has been studied experimentally and theoretically for decades. In RB6， metal atoms are embedded in a network of boron cages connected by B—B covalent bonds. This unique boron cage, the special 4f orbital and boron-deficient properties of rare earth elements make RB6 exhibit many excellent properties, such as low work function, high electrical conductivity, high emission current density, high hardness, high Young‘s modulus, high melting point, high chemical stability and strong resistance to heat radiation. RB6 materials are widely used in radar, aerospace, consumer electronics, instrumentation, nuclear power and other fields. Based on the structure and properties of RB6, this review describes the progress of its experimental preparation methods and theoretical density functional (DFT) research, summarizes its application in various fields, and finally gives our prospects.