Abstract: Hydrogen energy, as a clean, efficient and sustainable energy source, holds an important position in the current context of energy transition and sustainable development. However, there are still problems such as high production cost, difficult storage and transportation, insufficient infrastructure and significant safety challenges in the use of hydrogen energy. Among them, the storage and transportation of hydrogen are the core links in the utilization of hydrogen energy and have received extensive attention. Among various hydrogen storage methods, magnesium-based solid-state hydrogen storage materials can stably store hydrogen at normal temperature and pressure, greatly reducing the requirements for auxiliary equipment and safety risks, which hold broad application prospects. However, magnesium-based hydrogen storage alloys have high temperatures and slow kinetics during hydrogen absorption and desorption processes, which to some extent limit the application range of magnesium-based hydrogen storage materials. The addition of elements such as Ni, La and Mn can effectively improve the performance of Mg-based hydrogen storage materials. However, the dehydrogenation temperature and reaction kinetics mechanism of Mg-Ni-La-Mn hydrogen storage alloys are still unclear. To obtain the desorption reaction kinetics characteristics of Mg-Ni-La-Mn hydrogen storage alloys, this paper first prepared Mg-Ni-La-2Mn hydrogen storage alloys by induction melting method. Then, an experimental system was built to test the dehydrogenation kinetics performance of Mg-Ni-La-2Mn hydrogen storage alloys. Subsequently, based on the experimental results, the Johnson-Mehl-Avrami （JMA） kinetics equation and the dehydrogenation kinetics Arrhenius curve of Mg-Ni-La-2Mn hydrogen storage alloys were obtained. Finally, the kinetics equation of hydrogen dehydrogenation in Mg-Ni-La-2Mn hydrogen storage alloy was compiled into the Comsol software for numerical simulation to verify the reliability of the obtained JMA kinetics equation and Arrhenius curve. The dehydrogenation experiments of Mg-Ni-La-2Mn showed that when the dehydrogenation temperature was above 553 K, the alloy could achieve complete desorption within 2400 s. Increasing the desorption temperature could accelerate the desorption rate and reduce the desorption time. When the dehydrogenation temperature is 593 K, the maximum dehydrogenation amount and the time required for 80% dehydrogenation of the alloy sample were 6.19% （weight percentage） and 232 s, respectively. By analyzing the JMA equation and Arrhenius curve of Mg-Ni-La-2Mn alloy, the activation energy in the dehydrogenation process was found to be 66.67 kJ/mol, which was much lower than the values reported in the literature. The dehydrogenation process of Mg-Ni-La-2Mn alloy was numerically simulated and compared with the experimental data. The maximum error of hydrogen desorption amount was 2.81%, and the maximum relative error of temperature was only 0.04%, verifying the reliability of the established dehydrogenation reaction kinetics equation of Mg-Ni-La-2Mn hydrogen storage alloy.