<p>Herein, the influence of calcination temperature on the evolutionary process of Mg/Co species interaction in the MgCo₂O_<i>z</i> catalyst was studied for AP thermal decomposition. The results indicated that the as-fabricated MC-Na₂CO₃ catalyst by microwave irradiation assisting sodium carbonate co-precipitation method exhibited a typical flaky structure with non-uniform and coarse particle morphology, and the species of Co or/and Mg presented in an amorphous structure or/and a highly dispersed state. However, the calcination brought about the evolution of CO₂ due to the decomposition of carbonate, and the treatment of calcination at 200&#xa0;°C resulted in the formation of both MgCo₂O₄ and MgO crystals, which also promoted the interaction of Co and Mg species. Furthermore, the further enhancement of calcination temperature not only enlarged the growth up of spinel-structured MgCo₂O₄ crystals, but also decreased the diffraction peaks of MgO crystals through its proposed chemical reaction with Co species. This evolutionary process under the action of calcination at gradually increased temperatures regulated the chemical composition and states of elements on the surface of MC-Na₂CO₃ catalyst, and the surface Mg/Co molar ratio gradually decreased and then rebounded to 0.82 when the calcination temperature increases from 200 to 450&#xa0;°C. The as-fabricated MC-Na₂CO₃-350 catalyst presented the largest surface Co²⁺/Co³⁺ molar ratio and the best catalytic performance of AP thermal decomposition, which reduced the HTD temperature of AP by 150.8&#xa0;°C and increased its heat release to1685.48&#xa0;J&#xa0;g⁻¹. Finally, the influence of MC-Na₂CO₃-350 catalyst on AP thermal decomposition mechanism was discussed and proposed.</p>