Abstract: MgO/Mg(OH)₂ thermochemical heat storage technology possesses prominent advantages including low raw material cost, excellent environmental compatibility, high theoretical heat storage density, and good temperature matching characteristics with industrial low-temperature flue gas. It has broad application prospects in the fields of solar energy storage and industrial waste heat recovery, serving as one of the important technical approaches to alleviate the contradiction between energy supply and demand and promote the transformation of the energy structure.Nevertheless, magnesium-based heat storage materials still face multiple bottlenecks in practical dehydration-hydration cyclic processes. The gas diffusion channels are prone to blockage during the reaction, resulting in a remarkable increase in mass transfer resistance. Meanwhile, serious particle agglomeration occurs during cycling, which causes a continuous decline in dehydration/hydration conversion efficiency. Consequently, the actual heat storage density is far lower than the theoretical value, severely restricting the industrial advancement and large-scale application of this technology. This paper systematically reviews the modification strategies of MgO/Mg(OH)₂ thermochemical heat storage materials, and emphatically analyzes the influence mechanisms of functional carbon materials, salt additives and morphological structure regulation on the thermal storage performance of materials. It is clarified that modifiers can improve thermal conductivity, inhibit particle sintering and agglomeration, and optimize pore structure, thereby enhancing cyclic stability and reaction kinetic performance. Meanwhile, the influence laws of key operating parameters such as reaction temperature, pressure and steam flow rate on the heat charging/discharging cyclic stability of MgO/Mg(OH)₂ are summarized, providing theoretical support for practical process parameter optimization. In addition, the application status of MgO/Mg(OH)₂ heat storage technology in various reactors including fixed bed, fluidized bed, moving bed and rotary reactor is discussed, and the heat and mass transfer efficiency as well as industrial adaptability of different reactors are compared. Finally, combined with the current research bottlenecks in material modification, reactor design and system integration, the future research directions of this technology are prospected.