Spinel-type ceramics have great application prospects owing to their excellent thermomechanical properties in the field of high-temperature structural materials. In this study, a new approach that combined bond valence models with high-temperature mechanical theoretical characterization models was established to predict the high-temperature thermomechanical properties of spinel-type ceramics based on temperature-dependent crystal structure. Further more, the relationship between crystalline structure and high-temperature properties was clarified. The high-temperature fracture strength and fracture toughness of MgAl₂O₄ transparent ceramic, were predicted by this approach, which agreed well with the experimental values. It is shown that the ratio of cation inversion, hardness and bulk modulus of chemical bonds in MgAl₂O₄ vary significantly with temperature around 800 ℃. However, due to coupling effect of the coordinated polyhedra, the temperature-dependent cation inversion can hardly affect the high-temperature thermomechanical properties of MgAl₂O₄ transparent ceramic.