The magnesia-hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe working conditions. The synthesis of hercynite requires a suitable atmosphere with proper O2 partial pressures which makes sure FeO can stably exist at the synthesizing temperature. Current industrial production of hercynite mainly adopts fused method. The other method, sintering method, is not mature and needs further research. The magnesia-hercynite brick shows high hot toughness, high adhesion strength to kiln crust, and good corrosion resistance to alkali salt in cement kilns. The mismatching of thermal expansion between magnesia and hercynite can improve the thermal shock resistance of the bricks, but the oxidation of partial Fe2+, the high temperature solution, and low temperature exsolution of transgranular secondary spinel lead to cubical expansion, formation of more cracks, and poor thermal shock resistance of the bricks.