Spinel-type minerals can be classified into normal, inverse and disordered structure according to the different proportions of cation site occupancy at metal-oxygen tetrahedron and octahedron. In this paper, the authors chose micron-scale franklinite (ZnFe₂O₄) as the original research object. Mineralogical, thermal and magnetic measurements, such as SEM, XRD, XAFS, DTA-TGA, M-H, ZFC-FC, were employed to investigate the influence and mechanism of high temperature on the cation site occupancy. The results show that the cationic exchange occurs between ZnⅡ and FeⅢ in tetrahedral and octahedral sites, respectively, along with the increasing temperature. The maximum exchange rate appears at around 910°C. Thermodynamic and kinetic equilibrium is realized after the sample is heated at 1 200℃ for 24 hours. The cell parameter (a) decreases from 8.440 7 Ǻ to 8 437 2 Ǻ, and the Neel temperature (T_N) increases from 13 K to 27 K, changing antiferromagnetic order into the ferrimagnetic one. The particle size influences the energy of system, causing the completely opposite performance of cationic exchange for micro-ZnFe₂O₄ and nano-ZnFe₂O₄ at high temperature.