Abstract: Based on a 15 kW naturally aspirated intake hydrogen injection internal combustion engine, aiming at the matching problem of magnesium-based solid-state hydrogen storage devices and hydrogen internal combustion engines, the analysis of the coupling relationship between exhaust energy and dehydrogen energy under different loads was carried out under the condition of 3 000 r/min speed to investigate the effects of exhaust temperature and initial bed temperature on system efficiency. The results show that with the increase of the load of the hydrogen internal combustion engine, the dehydrogenation energy of magnesium-based solid-state hydrogen storage rises from 4.93 kW to 11.06 kW. When the exhaust energy of the hydrogen internal combustion engine is used for dehydrogenation, the power of the electric heater can be reduced by 6.07 kW at 100% load. The higher the exhaust temperature of the hydrogen internal combustion engine, the faster the reaction rate of the magnesium-based solid-state hydrogen storage device. The reaction can be completed within 6 000 s when the exhaust temperature is above 620 K. When the initial bed temperature of the magnesium-based solid-state hydrogen storage device rises from 560 K to 700 K, the hydrogen discharge time decreases from 14 400 s to 7 650 s, and the maximum efficiency decreases from 49.2% to 38.2%. When the hydrogen flow rate is 0.35 g/s, the higher the initial bed temperature, the lower the system efficiency. When the initial bed temperature is 636 K, the system efficiency is 36.5% which is the same as the original system efficiency. When the initial bed temperature is 560 K, the system efficiency is increased to 44.0%. But lower bed temperatures will cause the equilibrium pressure of the magnesium-based solid hydrogen storage system to be low, so the output pressure of the system can't match the hydrogen engine. The bed temperature of the magnesium-based solid-state hydrogen storage device is 610 K, which can meet the matching requirements of the magnesium-based solid-state hydrogen storage device and the hydrogen internal combustion engine, and the system efficiency is 39.0%, which is 2.5% higher than that of the original system.