Periclase-hercynite refractories are used in the firing zone of the cement rotary kiln, which is inextricably linked to their reaction behavior with cement clinker at high temperatures. In this paper, the corrosion behavior of magnesia aggregate and hercynite aggregate as well as periclase-hercynite refractory with cement clinker at high temperatures was investigated by scanning electron microscopy, X-ray diffraction, and Factsage simulation, respectively. The results show that magnesia particles have a superior corrosion-resistance to cement clinker, and the reaction of hercynite with cement clinker produces massive high-temperature liquid phase, which is gradually corroded. The periclase phase and hercynite particles have a synergistic effect on resisting the cement clinker corrosion in periclase-hercynite bricks at high temperatures. The periclase matrix as a major crystalline phase reacts with cement to generate a high melting point phase, forming a skeletal structure in the grain boundary phase, improving the grain boundary phase’s high-temperature viscosity, and promoting the combination of clinker and refractory. Also, ion exchange between hercynite and magnesia promotes the combination of hercynite and matrix, while inhibiting the formation of low melting point feldspar phases at high temperatures. Furthermore, the high-temperature stability of hercynite is improved, which benefits the kiln coating stability when using the refractory in the firing zone.